Image source, Getty Images

Let's step back from Los Angeles for some brief explanation.

Dozens of college campuses across the US have been taken over by students protesting against the war in Gaza.

Since the 7 October attack by Hamas and Israel's retaliatory assault, students have launched rallies, sit-ins, hunger strikes and, most recently, encampments against the war.

They are demanding that their schools, many with massive endowments, financially divest from Israel.

Divestment means to sell off stock in Israeli companies, or to otherwise drop financial ties.

Student activists say that companies doing business in Israel, or with Israeli organisations, are complicit in its ongoing war in Gaza - as are colleges investing in those companies.

• You can read more here

After clashes between pro-Palestinian protesters at UCLA and a rival group supporting Israel, one activist described the attacks faced by the former group as "relentless".

"Tonight they escalated to a whole new level, they started inciting violence," she told BBC News earlier.

The student, who spoke anonymously, said her cohort had faced "Zionist aggression every single night".

She said she was "thankfully physically safe", but "a lot of my peers are not physically safe".

UCLA's vice-chancellor earlier said there had been "horrific" acts of violence, and the police had been called in.

After confrontations between two rival groups at UCLA in California, Los Angeles police have now been seen on campus. It's just past 03:30, local time - and here are some of the latest snaps that have reached us.

Image source, AFP

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Image source, Reuters

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Today's edition of US Election Unspun - Anthony Zurcher's weekly newsletter about the race for the White House - will look at the potentially huge political ramifications of the Gaza protests for President Joe Biden ahead of November's election.

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Protesters and counter-protesters have clashed with sticks and other items at the University of California (UCLA) encampment in Los Angeles.

Watch the moment fighting breaks out, below.

A campus newspaper reporter was "tear-gassed" while covering the clashes at UCLA, according to Dylan Winward, who works for the Daily Bruin paper himself.

Pro-Israel counter-protesters, who showed up from around 22:00 local time (05:00 GMT), threw objects including "fireworks, a scooter, water bottles, and tear gas", Winward told BBC News a short time ago.

LA police have confirmed their officers have been deployed to campus after university administrators earlier declared an "unlawful assembly".

Winward said police presence was requested hours before, but had only just arrived.

Meanwhile, a university-appointed security team has withdrawn, Winward says, because they believed they could no longer "safely hold" the buffer zone.

It is not clear what caused Tuesday night's outbreak in violence, but there are reports that the counter-protesters knocked over a barrier that formed a "buffer zone" between the two groups.

After last night’s police raid in Columbia University, now the spotlight's on UCLA in California, where clashes have broken out between the two rival groups of protesters.

Let’s look at what we know so far:

• The university's vice-chancellor Mary Osako says "horrific acts of violence occurred at the encampment tonight” and that law enforcement has been called
• Tensions have been building, and it's not clear what caused the overnight outbreak. Footage online appears to show people throwing things at the pro-Palestinian camp, and fireworks being set off
• The Los Angeles mayor's office says the city's police department is responding to the university's request for help. We have seen footage of police appearance at the campus
• Earlier, at Columbia University in New York, a number of of pro-Palestinian protesters were arrested in a raid on Hamilton Hall, an academic building that was taken over by activists

• Police said they had cleared all the protesters from Hamilton Hall, after the university authorities authorised the raid

Image source, Reuters

Earlier, the focus of this page was on police's forced removal of protesters who were occupying a building at Columbia University in New York. That clash was between police and pro-Palestinian demonstrators.

But what we're seeing happening on the other side of the country at UCLA appears to be violence between pro-Palestinian and pro-Israel groups.

Some context: these tensions have been building for some time, as both sides have mounted protests on the Los Angeles campus in recent days. What's triggered this sudden violence between both sides is not yet clear.

Security guards at first were just observing the clashes but not stepping in to stop them, the Los Angeles Times reports. The university said police had been called.

Image source, ABC7

We can see from the live stream - which you can watch at the top of this page - that police cars have arrived on the campus.

The Los Angeles mayor's office has in the past half-hour posted on X that the city's police department "is responding immediately to (the university authorities') request for support on campus".

The university's authorities have commented on the violence that's broken out at UCLA, saying law enforcement has been called.

"Horrific acts of violence occurred at the encampment tonight, and we immediately called law enforcement for mutual aid support," vice-chancellor Mary Osako said.

Image source, ABC7

There's a fast- moving situation at the University of California, Los Angeles (UCLA) where student protesters had been holding their own lawn protests.

It's just past 01:00 in the early morning there, but clashes have broken out between rival protest groups in the past hour.

On social media, there are reports that pro-Israel demonstrators started attacking the pro-Palestinian camp in the night.

We have seen footage of people throwing things at those in the camp, and fireworks being set off.

Some protesters wearing masks had arrived in the middle of the night in attempt to tear down the barricades, the Los Angeles Times newspaper is reporting.

On the other side of the country, an encounter appears to be taking place between rival protest groups at UCLA, at the University of California Los Angeles campus.

We have vision of what's happening there - watch live by clicking the play button at the top of this page.

Earlier we had a dispatch from our reporter on the ground, Alex Lederman, who was talking to a student protester when police interrupted.

The student had been describing how police had physically handled students.

Watch the full interview below:

Columbia University has been one of the main battlegrounds in the pro-Palestinian protests that have gripped US college campuses. But the last 24 hours also saw arrests at other universities, according to US media reports.

City College New York: Dozens arrested during a night-time protest at the campus in Harlem

University of North Carolina Chapel Hill: At least 36 protesters detained at a tent protest

Florida University: Five people arrested

Image source, Getty Images

Nomia Iqbal
BBC News, Columbia University

More than 36 hours ago, we were inside the Columbia campus.

We’d heard that protesters in the encampment on the lawn had been told to clear by 14:00 local time (18:00 GMT) on Tuesday.

Media started lining up outside as police erected barriers, with some officers carrying zip wires. There was a sense that something was coming.

When we got inside the encampment itself, it was peaceful - protesters were bathing in the sun, doing school work on their laptops and making sure everyone was fed.

Image source, Getty Images

Some were worried police would come in again - but others suggested they wouldn't, given the controversy that ensued after riot police arrested students on 18 April.

Dozens of faculty linked arms to guard the entrance of the encampment. There was a real sense of "the police better not try this again".

Before we left the campus on Monday night, we heard negotiations between students and the university administration had broken down.

But Mahmoud Khalil, lead negotiator and a Columbia student, told us he was optimistic they could get back on track.

On Tuesday we woke up to news that a building inside Columbia had been broken into and occupied, and negotiations fell apart even faster.

Khalil later told us he had been suspended from Columbia. A Palestinian from Syria, he is reliant on a visa to be here. He said he had been promised protections given his position as a negotiator - but he is now unsure about what might lies ahead.

Image source, Getty Images

Good morning - if you're just joining us, here's what unfolded late on Tuesday night at Columbia University in New York:

• Police arrested dozens of pro-Palestinian protesters in a raid on Hamilton Hall, an academic building that was taken over by protesters nearly over 24 hours before
• One student told the BBC that about "80 - 100" police officers had stormed the hall, with local reports saying that flash bang devices were used to disorient protesters
• Unusual and tense scenes were captured at the ivy league university: police in riot gear climbing a ladder to enter the second storey of Hamilton Hall, and then protesters being led out and taken away in police buses as others gathered and even cheered for them

• Columbia authorised the raid after demonstrators defied a deadline to disperse. After the hall was "occupied, vandalised and blockaded, we were left with no choice", the university said
• Police later said they had cleared all the protesters from Hamilton Hall - and a tent camp on the lawns that had been around for nearly two weeks
• US universities have been gripped by protests as students demand a boycott of companies and individuals with ties to Israel during the war in Gaza
• The scene has now quietened as students who were stuck outside during the standoff have begun to return to campus

Stay with us as we bring you the latest.

New York Police brought down the Palestinian flag at the City College of New York, replacing it instead with the American flag, according to footage posted by the NYPD's Deputy Commissioner, Kaz Daughtry.

In his post on X, formerly known as Twitter, he described it as an "incredible scene and proud moment".

Police arrested dozens of pro-Palestinian protesters during a night-time raid at Columbia University - nearly 24 hours after they had taken over an academic building.

Here's a quick recap of what happened:

Columbia University President Nemat Shafik has asked police to stay on at the university for another two weeks until 17 May, which is two days after the university's graduation ceremony day.

A letter has emerged of Shafik making the request for police to intervene and clear out the students who had camped at Hamilton Hall.

She said the university had been left "with no choice" but to request the action.

"The takeover of Hamilton Hall and the continued encampments raise serious safety concerns for the individuals involved and the entire community. The actions of these individuals are unfortunately escalating," she had written.

She had also outlined how the protests had been ongoing since 19 April, with encampments first on the West Lawn and then the Math Lawn of the campus.

"In light of the activities that occurred after the events of April 17-18, 2024, we further request that you retain a presence on campus through at least May 17, 2024 to maintain order and ensure encampments are not re-established."

Pratiksha Ghildial
Reporting from Columbia University

It’s all gone pretty quiet where we are now - just outside campus.

Officers have started opening up some roads leading to it, though scores of police officers are still milling about.

Police say all students who live on campus and were stuck outside are now being allowed to go back inside.

Image source, BBC/Pratiksha Ghildial