Moscow concert hall attack: What we know so far as death toll rises to 133 and Putin says all four ISIS gunmen arrested

Many Russian civilians were killed on Friday night in Moscow after an ISIS attack saw four armed men gun down innocent people. 

A total of 133 have died as a result of the onslaught that was carried out just before a concert in Krasnogorsk, on the outskirts of Moscow.

It was the deadliest attack to happen in Russia for years and left the music venue in flames.  

Here is everything we know about what happened on that dreadful evening.

A total of 133 have died as a result of the onslaught that was carried out just before a concert in Krasnogorsk, on the outskirts of Moscow. Pictured: Image of the suspected gunmen who opened fire at Crocus City Hall, in Krasnogorsk, Moscow

It was the deadliest attack to happen in Russia for years and left the music venue in flames. Pictured: The Crocus City Hall concert hall engulfed in flames as the venue is surrounded by emergency service crews

How did the attack unfold?

Unsuspecting concertgoers had gathered at the Crocus City Hall on the outskirts of Russia's capital to watch rock band, Picnic, on March 22. 

The four suspected terrorists were spotted arriving in an unmarked white van shortly before the attack took place. 

They were armed with Kalashnikovs, according to witnesses, and the foursome began shooting as they entered the venue just before 8pm.

Shots were fired at people waiting in the foyer and bodies were seen in footage shared to social media falling one after the other as the terrorists made their way to the concert hall area.

Civilians tried to escape the building in a panic and were forced to duck down while the gunmen fired at the crowd.

A fire was then started by the suspected terrorists that then went on to consume much of the huge building that can hold up to 6,000 people. 

Russian news reports cited authorities and witnesses as saying the attackers threw explosive devices that started the fire, which eventually consumed the building and caused its roof to collapse.

Emergency services arrived at the scene and were able to get into the building to help treat the wounded after the blaze was put out by firefighters.  

Unsuspecting concertgoers had gathered at the Crocus City Hall on the outskirts of Russia 's capital to watch rock band, Picnic, on March 22 

The four suspected terrorists were spotted arriving in an unmarked white van shortly before the attack took place 

They were armed with Kalashnikovs, according to witnesses, and the foursome began shooting as they entered the venue just before 8pm. Pictured: A video grab showing people evacuating the Crocus City Hall

Emergency services arrived at the scene and were able to get into the building to help treat the wounded after the blaze was put out by firefighters. Pictured: Rescuers working inside the venue a day after the massacre

Who is responsible for the incident? 

That same evening, the Islamic State claimed responsibility for the attack and said four of its members were involved.

It is thought the men who carried out the attack all worked for ISIS-K, an offshoot of ISIS that is known for its barbarity that was set up in late 2014 in eastern Afghanistan in the wake of US-led airstrikes against ISIS strongholds across Iraq. 

ISIS news agency Amaq has also recently released a graphic video of the attack in Crocus City Hall.  

That same evening, the Islamic State claimed responsibility for the attack and said four of its members were involved. Pictured: The blaze at the Crocus City Hall

Pictured: Two of the suspected gunmen in a white Renault car

Who has been arrested? 

Russian authorities said on March 23 that they had arrested 11 people including four suspected gunmen in connection with the attack.

A white Renault car with the alleged terrorists was stopped in the Bryansk region close to the borders with Belarus and Ukraine, according to Baza media.

Videos online also show some suspects being detained - with one shaking on his knees and apparently confessing to carrying out the attack.  

Photographs and the names of four suspects have also been released by Baza.

It is unclear which of these four have been detained. 

A video shared online shows one suspect shaking on his knees and apparently confessing to carrying out the attack 

A second suspect was filmed arrested with his hands tied behind his back 

More footage showed a third suspect, who had what appeared to be blood across his face, being moved along a path and restrained by men

Who are the victims?

At least 133 innocent civilians have been confirmed dead and around 150 were left injured, as of Saturday afternoon. 

Some of the victims were reportedly mothers and children.

One of the fatalities, listed by the Russian Health Ministry, was 42-year-old former beauty queen Ekaterina Novoselova.

Another victim was Natalia Zudina, 44, a graduate of the Ural State Economics University, originally from Yekaterinburg. 

An eight-year-old boy was among those injured and is said to be in a critical condition in hospital. 

Russian President Vladimir Putin announced March 24 as a day of national mourning in an address that was televised to the country, according to Russian news agency Tass.

At least 133 innocent civilians have been confirmed dead and around 150 were left injured, as of Saturday afternoon. Pictured: People lay flowers and light candles standing next to the Crocus City Hall

One of the fatalities, listed by the Russian Health Ministry, was 42-year-old beauty queen Ekaterina Novoselova (pictured) 

An eight-year-old boy was among those injured and is said to be in a critical condition in hospital. Pictured: Concertgoers leave the building as armed terrorists open fire 

What does Putin claim? 

In a national address, the Russian leader accused Ukraine of assisting the terrorists behind the attack.

Putin claimed that the attackers had escaped from the scene in a white Renault and were about to cross the border into Ukraine.

He said: 'They tried to hide and moved towards Ukraine, where, according to preliminary data, a window was prepared for them on the Ukrainian side to cross the state border.'

Ukraine has denied involvement in the attack. 

A spokesman for Ukraine's President Volodymyr Zelensky denied any involvement in the attacks, and said: 'Ukraine has never resorted to the use of terrorist methods. Everything in this war will be decided only on the battlefield.' 

In a national address, the Russian leader (pictured) accused Ukraine of assisting the terrorists behind the attack 

Putin claimed that the attackers had escaped from the scene in a white Renault and were about to cross the border into Ukraine. Pictured: A woman wipes away a tear as she gathers with other mourners in front of the Crocus City Hall

What has America said? 

Officials in America claim that intelligence agencies had collected information in recent weeks that ISIS was planning an attack in Moscow and shared the findings with Russian officials.

However, there are also claims that the warnings were dismissed by Putin.

The American Embassy in Moscow also put out a security alert earlier in the month and urged people to avoid large crowds. 

Concerts were specifically mentioned as a potential target in the alert.

It is not clear what prompted the warning or whether it was related to the attack on March 22.

American officials also refute Putin's claims that Ukraine is responsible.

'ISIS bears sole responsibility for this attack. There was no Ukrainian involvement whatsoever,' National Security Council spokeswoman Adrienne Watson said in a statement.