Columbia University has just released a statement on tonight's events.

Here's the statement in full:

"A little after 9pm this evening, the NYPD arrived on campus at the University’s request. This decision was made to restore safety and order to our community.

"We regret that protesters have chosen to escalate the situation through their actions. After the University learned overnight that Hamilton Hall had been occupied, vandalized, and blockaded, we were left with no choice. Columbia public safety personnel were forced out of the building, and a member of our facilities team was threatened. We will not risk the safety of our community or the potential for further escalation.

"The leadership team, including the Board of Trustees, met throughout the night and into the early morning, consulting with security experts and law enforcement to determine the best plan to protect our students and the entire Columbia community. We made the decision, early in the morning, that this was a law enforcement matter, and that the NYPD were best positioned to determine and execute an appropriate response.

"We believe that the group that broke into and occupied the building is led by individuals who are not affiliated with the University. Sadly, this dangerous decision followed more than a week of what had been productive discussions with representatives of the West Lawn encampment.

"We severely curtailed the number of people on Morningside campus starting Tuesday morning. Over the course of the day, we updated our community on access to campus buildings, and will continue to do so through the next few days.

"The decision to reach out to the NYPD was in response to the actions of the protesters, not the cause they are championing. We have made it clear that the life of campus cannot be endlessly interrupted by protesters who violate the rules and the law.

"Early Tuesday, protesters chose to escalate to an alarming and untenable situation – including by vandalizing property, breaking doors and windows, blockading entrances, and forcing our facilities and public safety workers out – and we are responding appropriately as we have long made clear we would. The safety of our community, especially our students, remains our top priority."

This was the scene outside the university before police went in to clear the occupied building. We'll have more footage of the police operation as we get it.

Bernd Debusmann Jr
US Reporter

One of the main groups involved in the protest, Columbia Students for Justice in Palestine, has been tweeting even as the police operation to clear Hamilton Hall continues.

"To be clear, Columbia University has called the cops onto its own students for the second time in two weeks, on the 56th anniversary of when they last called police onto campus to arrest over 700 protesting the Vietnam War [and] Harlem gentrification on April 30th, 1968," one recent tweet said.

A video posted by the group appears to show police moving observers - which it said includes "legal observers" and journalists - away from the area.

"They do not want us to bear witness to their brutality," the group said.

The BBC has been unable to independently verify what the video shows.

Images being broadcast on US media outlets show detainees in NYPD buses that have been brought into the area.

We've just had confirmation from the NYPD that they've entered Hamilton Hall, which was occupied by protesters last night.

The situation is still very fluid at the moment and it is unclear how many officers are inside the hall or how many people have been taken into custody.

Images on TV appear to show officers using a large mobile ladder - similar to a crane - being used by officers to enter.

Stay with us for more updates.

Image source, Getty Images

Nomia Iqbal
Reporting from Columbia

We're currently at Columbia University, where we're separated from the protest encampment by a line of police officers. We can't get in.

Protesters and their supporters outside the campus are chanting "shame" and "shame on Columbia" as the operation begins.

One officer could clearly be heard saying "I have no idea what's going on" from inside the barricades.

Just a little while ago, we saw several individual protesters taken away by NYPD officers after breaching the barricades.

Bernd Debusmann Jr
US Reporter

At the moment, hundreds of police officers are gathered outside Columbia University, where Gaza war protesters have occupied Hamilton Hall and so far refused to move.

New York police say the operation has "commenced".

One of the main student groups involved in the protest, Columbia Students for Justice in Palestine, posted a message on X warning that "mass arrests are expected".

The group also called on people to come to campus to "stand up for students".

Stay with us for more updates.

Welcome back to our coverage of the US university protests against the war in Gaza.

In New York, police have massed outside the Columbia University campus, where students had earlier taken over a building and broken windows, and were reported to be moving in.

Our partner in the US, CBS News, has confirmed reports that New York police had received authorisation from Columbia to enter the campus.

The university also issued a "shelter in place" order, according to CBS, to all students as police officers mass to end the protest. It had earlier told the protesters they must leave or face being expelled.

Here are pictures from outside the campus from earlier, with police in riot gear and protesters at the entrance gates.

We are pausing our live coverage for now after another hectic day of protests across several US college campuses.

Tiffany Wertheimer, Jessica Murphy and Aoife Walsh edited this page. The writers were Sam Cabral, Ana Faguy, Madeline Halpert and Brandon Drenon.

We'll leave you with our look at how officials dealt very differently with protests at Northeastern University in Boston and Northwestern University near Chicago.

Read it here.

Tom Bateman
BBC News, UT Austin

We arrived at the University of Texas at Austin shortly after lunchtime, where a small group of around 40 or 50 people was protesting against the war in Gaza.

Some wore Palestinian keffiyehs, others held handwritten signs calling on the university to divest from arms to Israel. They sat on the lawn and held a question-and-answer session among their group, including some faculty members, on topics from the jailing of demonstrators to the right to free speech.

The site is now clear of tents and tables after the university administration called in Texas state troopers on Monday. Riot police armed with batons, bolt cutters and pepper spray moved in on the encampment, dragging people away and making more than 100 arrests, according to local media.

“We were receiving a show of violence by the police,” said one of the demonstrators who asked that his name was not published.

“They started picking people off one by one, arresting them, throwing them on the ground, pulling them by their legs, their hair, their shirt. They pulled everybody out,” he told me.

As tensions mounted on Monday, the Republican Governor of Texas, Greg Abbott, weighed in, saying: "No encampments will be allowed… instead, arrests are being made."

Some 50 people are still being held by police, according to protesters. They accuse the university authorities of helping facilitate a violent crackdown on free speech. University officials blame demonstrators for escalating tensions by ignoring calls to remove the encampment - a claim the protesters reject. UT Austin said many present on Monday were not from the university.

Near the protest today a smaller group of counter-demonstrators stood at the edge of the lawn, each wrapped in an Israeli flag. The site has been mostly calm aside from a few isolated moments of friction between the two groups.

Image source, Getty Images

The White House is considering allowing some Palestinians to come to the US as refugees as people continue to flee the fighting in Gaza, CBS News, the BBC's US partner, reports.

Documents obtained by CBS show Biden administration officials are considering offering a US resettlement option for Palestinians from Gaza who have immediate family members who are American citizens or permanent residents.

The exact number of people potentially eligible is unclear, but CBS reports the number is small. Palestinians who make it to the US with refugee status may see resettlement benefits such as housing assistance and a path to citizenship.

Nomia Iqbal
Reporting from Columbia University

Mahmoud Khalil, one of the student organisers at Columbia University, told us he woke up to an email saying he had been suspended from the university, despite his role in negotiations between students and Columbia officials.

"I was so surprised," he said of his suspension.

Administrators at Columbia University have just held another media briefing this evening, as reporters continue to have limited access to the school's partially-occupied Morningside campus.

Spokesperson Ben Chang declined to share specifics of latest developments, only saying that leaders were still "exploring options to restore safety".

Chang reiterated that Columbia is "following through with the consequences we outlined yesterday" - including suspension from use of facilities and premises. Earlier, he confirmed that those occupying Hamilton Hall face expulsion.

Brandon Drenon
BBC News

Melissa Manesh is a senior at the University of Southern California, where ongoing pro-Palestinian protests have tossed the campus into turmoil - so much so that its main graduation ceremony has been cancelled.

"This was one of the biggest moments that we've all been waiting for, and now we're not going to able to experience that," she says.

Melissa adds that her campus - now in "chaos" - has been a source of frustration during a time when "we're supposed to be so happy".

She describes colleagues being arrested, helicopters hovering overhead as she tries to study, vandalism on school monuments, and encounters with antisemitism.

Protests at New York's Columbia University have become a focal point for the country's debate over the war in Gaza and US support for Israel.

Pro-Palestinian demonstrations at Columbia escalated overnight, after protesters broke into an academic building called Hamilton Hall - which they have renamed Hind's Hall, in memory of a young girl found dead in Gaza earlier this year.

Here's a look at some of the latest developments:

• The university is currently restricting campus access; it has also suspended students who didn't comply with its deadline to leave their encampment by 14:00 local time yesterday - and has warned those occupying Hamilton Hall face expulsion
• Lead Columbia negotiator Mahmoud Khalil told the BBC he had complied with the university's order but had nevertheless been suspended - and is now at risk of losing his US student visa
• Organisers say they have "no plans to end their protest anytime soon"

• There is growing criticism from many corners, with both President Joe Biden, his predecessor Donald Trump and leaders of both parties denouncing the Hamilton Hall takeover
• Elsewhere, police - mostly in riot gear - detained dozens of protesters at similar protests, including on the campuses of the University of Texas at Austin, Virginia Commonweath University and California State Polytechnic University, Humboldt

• A few universities facing protests have struck accords to end their encampments peacefully and without law enforcement intervention, including Brown University in Rhode Island and Northwestern University in Illinois

Stay with us for more.

Let's take a look now at some of the the latest pictures from Hamilton Hall, currently occupied by student protesters:

Image source, Reuters

Image source, Reuters

Image source, Reuters

Image source, Getty Images

Columbia University has emerged as the epicentre of demonstrations that spread across the country after the college's president requested earlier this month that protesters there be removed, leading to arrests.

Over the past 24 hours, dozens of the pro-Palestinian protesters have escalated their demonstrations by occupying an academic building on Columbia's campus, Hamilton Hall.

Columbia has urged staff and students to stay away as the group has barricaded themselves inside the hall. They have limited access to the campus to students living in residential buildings there.

The takeover began after Columbia started suspending students who defied a deadline of 14:00 EST (18:00 GMT) on Monday to leave their two-week encampment nearby.

You can learn more about the situation here.

Image source, Getty Images

Senate majority leader Chuck Schumer, a Democrat from New York, has critiqued protesters who overtook Hamilton Hall at Columbia University on Monday.

During remarks on the senate floor earlier, Schumer said "smashing windows with hammers and taking over university buildings is not free speech".

"It is lawlessness and those who did it should promptly face the consequences," he added.

University students are not the only ones protesting the Israel-Hamas.

At a high school in Austin, Texas, around 100 students walked out of class yesterday and marched around their school campus chanting: “Students together can make the world better", according to local outlet Austin American-Statesman.

Others in the Austin high school district also protested in support of Palestinian people, the news outlet said.

They were joined by high schoolers in the western state of Washington who also walked out of class today in protest.

Sam Cabral
BBC News

Image source, Reuters

We've been hearing a lot about Hamilton Hall today, which is the academic building protesters at Columbia University have forcibly taken over.

The building, opened in 1907, is on the university's Morningside campus in New York City. It's an eight-storey building home to the Slavic and Germanic language, and classics departments, and it's named after Alexander Hamilton, one of the men known as the Founding Fathers of the United States.

But there is symbolism in its seizure.

Back in 1968, Columbia students protesting the Vietnam War and in favour of the Civil Rights Movement for black Americans occupied the building and several others exactly 56 years ago to the day.

In the end, police violently cleared that demonstration, with more than 700 arrests and some 150 people injured.

Echoing language from that protest, an Instagram account affiliated with Columbia University Apartheid Divest - one of the main groups involved in this occupation - wrote: "This building has now been liberated".

In a press release, the group said community members have "reclaimed" the site in honour of Hind Rajab, a six-year-old girl found dead in February after going missing while trying to flee Gaza City with relatives.

Her final pleas for someone to help her before coming under Israeli fire - heard on a phone recording - reverberated around the world.

Image source, Getty Images

Students with the Columbia University Apartheid Divest spoke a short time ago at a news conference about their ongoing protest at the Hamilton Hall campus building.

A spokeswoman for the group, who say she would not give her name as some protesters' families had been receiving threats, said that no official negotiations were taking place with university leadership.

"We believe there's strong evidence that Columbia does not and never has wanted to bargain in good faith," she said.

Calling on leaders not to send police into the occupied building, and for food and water to be allowed in, the spokeswoman said about 60 people were inside.

"In terms of how negotiations will resume, I think that is largely in the hands of the university.

"And it's up to them to commit to not threatening us with food insecurity, and soldiers and militarised police."