Children have been injured in the shooting at the Moscow concert hall this evening, according to Russia's Ria news agency, which quoted a Moscow official.

An anonymous eyewitness said earlier that a number of children and teenagers had been performing in a ballroom dancing competition when the shooting started. Their parents were also in attendance.

“Children and teenagers were at the competition. People came and said there was shooting. A crush ensued. The children were running out in their ballroom gowns,” they said.

The US embassy in Moscow has issued a statement saying it is "shocked" by the attack and expressing "sincere condolences" to the Russian people.

The embassy is advising US citizens to avoid the area where the attack took place.

It has also warned that the US government is "severely limited" in its ability to help its citizens in Russia far from the Moscow embassy. They said the Russian government had limited the ability of US personnel to travel.

As we've reported, the US issued a warning to its citizens two weeks ago saying that officials were "monitoring reports that extremists have imminent plans to target large gatherings in Moscow, to include concerts."

The warning urged Americans to avoid large gatherings for 48 hours. That time period has passed, but the similarities between the warning and today's events suggest a link might be possible.

The Russian rock band Picnic were due to perform at the concert hall when the attack took place.

They have now posted on Instagram to say they are "alive and safe".

"There was a tragedy that took place, the scale of which we can't yet assess," their statement said.

"We are following the news and awaiting official information. The musicians and management are alive and safe."

Image source, Reuters

Firefighters have managed to stop the massive fire at the city hall from spreading, Russian news agency Interfax is reporting.

The Russian national guard are searching for the perpetrators of the attack on Crocus City Hall.

At least 40 people have died and more than 100 others are injured, according to the FSB, Russia's Federal Security Service.

Image source, Reuters

Russian President Vladimir Putin is getting regular updates on the situation at Crocus City Hall, according to Dmitry Peskov, the Kremlin spokesman.

"Vladimir Putin was informed about the beginning of the shooting in the first minutes of what happened in Crocus City Hall," Peskov says.

The Crocus City Hall in Krasnogorsk, a suburb to the north-west of Moscow, is known to host several thousand people and has hosted top international artists.

Video on social media showed several armed men entering the lobby before they opened fire.

The attack took place before the start of a concert by Picnic, a popular rock band that previously said on Instagram, external that it had sold out the venue.

Up to 6,200 tickets had been sold for tonight's gig, according to Russian media, but we don't yet know exactly how many people were inside at the time of the attack.

Russian media outlets also reported that members of the band were not harmed during the shooting.

Verifying footage from the incidentpublished at 20:01 Greenwich Mean Time 22 March

20:01 GMT 22 March

People have been filming on their phones from inside the concert hall and posting it on social media. At BBC Verify, we’ve been piecing together the story as it unfolds.

One video we’ve verified begins with people starting to leave the hall after something appears to have gone wrong.

Suddenly gunshots ring out, and people start screaming and running in panic.

It’s difficult at this point to know how many people are involved in the incident, but in one video we can see a large number of people in the hall.

Another video we’ve verified from inside the hall shows a close-up of what appear to be gunmen shooting indiscriminately.

Four gunmen are seen in a third video shooting in the venue's foyer. Several casualties are on the floor.

We’ve also verified videos filmed from outside the concert hall which appears to show the building on fire with large plumes of smoke coming out.

This is still a developing story and we’re continuing to verify and analyse footage emerging from the incident.

Paul Kirby
Europe digital editor

A security guard on duty at the central entrance to the hall has given an eyewitness account to Telegram channel Baza. We can't corroborate his account but it does correspond with some of the video that has emerged online.

He describes how he and three colleagues all survived the attack:

"When the shooting began I was standing at the central entrance on the ground floor.

"They started shooting from outside and the windows shattered. Next to the entrance there were three other security guards and they hid behind an advertising board. And those attackers walked past us 10m (30ft) away.

"They started shooting randomly at people on the ground floor and went towards either the concert hall or the oceanarium.

"When the shooting stopped, we went out through the central exit and administrators were already helping the wounded."

Image source, EPA

Yulia Navalnaya, the widow of Russian opposition leader Alexei Navalny, has expressed her condolences to the victims of today's attack, calling it a "nightmare in Crocus".

"All those involved in this crime must be found and brought to justice," she wrote on X, formerly Twitter.

We're hearing now from an aide to Ukrainian President Volodymyr Zelensky, who has distanced his country from the attack near Moscow.

In a Telegram post, Mykhailo Podolyak said "let's be clear, Ukraine absolutely has nothing to do with these events".

A reminder that Ukraine and Russia have been at war for the last two years, after Russian forces invaded Ukraine in February 2022.

Paul Kirby
Europe digital editor

Image source, Ria Novosti

Fire has engulfed the roof and facade of Crocus City Hall and smoke and flames are visible across the skyline in the centre of Krasnogorsk.

A Tass state news agency correspondent says around a third of the building has been set alight.

Other reports speak of explosions where the glass on the top two floors of the structure has been broken by the force of the blaze.

Part of the roof close to the theatre is said to have collapsed.

Some of those who tried to escape from the gunmen are thought to have fled to the basement, and others to the roof.

Here is Russia's Federal Security Service, the FSB's, full statement:

All possible measures are being taken to provide assistance to those affected as a result of the terrorist attack in the Crocus City Hall.

The special services are carrying out active search measures following the emergency in the Crocus complex.

According to preliminary information: 40 dead and over 100 wounded.

More images are coming in from outside the Crocus City Hall venue,

Police and special operations forces are there alongside firemen and medical personnel, to deal with both a growing fire and a deadly shooting.

Image source, Reuters

Image source, Getty Images

Image source, Reuters

Image source, Reuters

Image source, Reuters

Steven Rosenberg
Moscow correspondent

Image source, Getty Images

A number of special forces groups have stormed the concert venue.

The building is on fire.

There are some reports about concerns one of the floors might collapse and there's also concern people are still trapped inside.

The Moscow mayor, Sergey Sobyanin, has called this a “terrible tragedy”. The Russian Foreign Ministry has called it “a bloody terrorist attack”.

Some reports suggest that possibly at least one of the gunmen may have escaped and is being looked for by police.

It’s a chaotic situation, and not clear exactly what is happening right now. What is clear is that there are going to be a lot of casualties from this and it’s a shocking incident.

Gordon Corera
Security correspondent, BBC News

It is too early to know who was responsible for this attack.

But it is notable that two weeks ago, the US issued an unusual warning to its citizens in Russia. It was "monitoring reports that extremists have imminent plans to target large gatherings in Moscow, to include concerts”.

The message said US citizens should avoid large gatherings over the next 48 hours.

Despite the delay, the similarity in the nature of the target suggests a link might be possible. But there was no indication of who those extremists might be.

The White House has quickly said there is no indication that Ukraine or any Ukrainians were involved in the attack, with a spokesperson saying they wanted to "disabuse" reporters of any connection.

There have been attacks in Moscow in the past – most notably a siege at a Theatre in 2002 which was linked to Chechen fighters.

About 40 people have been killed and more than 100 others were wounded in the attack at the Moscow concert hall, according to Russia's Federal Security Service, the FSB.

Just over two weeks ago, on March 7, the US embassy in Moscow issued a security alert after receiving reports that "extremists have imminent plans to target large gatherings in Moscow, to include concerts".

At the time, US citizens were advised "to avoid large gatherings over the next 48 hours".

Paul Kirby
Europe digital editor

Video showing apparently heavily armed gunmen has appeared online, from within Crocus City Hall, where the group Picnic were preparing to play. This hall is just to the north-west of Moscow in the town of Krasnogorsk.

There have been some reports of up to five shooters inside the hall and that they have barricaded themselves in the building.

One video posted online shows several men striding across the concourse outside the hall opening fire at members of the public, before rearming and then going into the hall.

Another video shows them apparently opening fire from a seating area inside the hall.

The hall has a capacity of several thousand seats and Picnic are a well-known band dating back to the 1970s.

Latest reports say helicopters are trying to douse the fire which has spread across the building.

Here's a map showing the location of Crocus City Hall, the concert venue under attack this evening. It's located just north of the Russian capital Moscow.