Death toll from Moscow concert hall attack rises to 133. The FSB confirmed 11 suspects have been arrested.

• 133 people are reported to have died in a terrorist attack on Moscow's Crocus City Hall on Friday.
• ISIS-K, based in Afghanistan, claimed responsibility for the attack in a statement.
• The FSB claim to have arrested 11 suspects in connection with the attack.

The death toll from the attack on Moscow's Crocus City Hall Friday night has risen to 133 as Russia's Federal Security Bureau confirmed eleven suspects had been arrested in connection with the attack.

According to Russia's Investigative Committee: "The death toll will rise further. According to preliminary data, the causes of death were gunshot wounds and poisoning by combustion products."

The death toll stands at 133, the Investigative Committee said on Saturday.

Islamic State has claimed responsibility for the attack, though neither the Kremlin nor Russian security services have yet assigned blame officially.

TASS reported that Picnic, a Russian rock band, was scheduled to perform just before the attack. The concert hall can accommodate about 6,200 people, according to The Associated Press.

"Preliminary results of the inspection of the premises of the concert hall indicate that the terrorists used automatic weapons during the attack, which, along with the ammunition they left behind, were discovered and seized by (investigators)," the committee said Saturday.  

"Based on this material evidence, ballistic, genetic and fingerprint examinations are currently being carried out," it added. 

"It was also established that the terrorists used a flammable liquid to set fire to the premises of the concert hall."

One hundred fifteen people have been injured, including five children, Andrey Vorobyov, governor of the Moscow region, said.

The Ministry of Health in the Moscow region has since published the identities of 41 of those known to have been killed in the attack. The youngest victim identified so far is a 33-year-old, and the oldest is 71.

Russian President Vladimir Putin has yet to make a public statement on the attacks. However, his spokesperson, Dmitrii Peskov, told reporters that "the president constantly receives information through all relevant services about what is happening and about the measures being taken. The president is giving all necessary instructions."

Arrests

Russia's FSB confirmed that 11 people had been arrested in connection with the attack on the concert hall.

In a statement reported by Russian media, the FSB said: "As a result of the actions of the special services and law enforcement agencies, 11 people were detained, including 4 terrorists who were directly involved in the terrorist attack in Crocus City Hall."

"After the terrorist attack, the criminals intended to cross the border of the Russian Federation and Ukraine and had relevant contacts on the Ukrainian side, the FSB said," the FSB report reads, according to state media RIA Novosti.

State-owned Russian news agency TASS also reported that the assailants had "contacts on the Ukrainian side."

Neither agency specified the nature of the alleged contacts.

On Friday, Ukrainian presidential advisor Mykhailo Podolyak said that Kyiv had "nothing to do with the attack."

"Ukraine has never resorted to the use of terrorist methods," he wrote on X.

Why ISIS-K is claiming responsibility

Shortly after the assault, the Islamic State Khorasan Province, or ISIS-K, a branch of the jihadist group in Afghanistan, claimed responsibility for the attack in a statement shared with the ISIS-affiliated news agency Amaq on Telegram, CNN reported.

According to The New York Times, US officials confirmed the group was responsible.

An unnamed US intelligence officer told The Associated Press that US intelligence agencies had confirmed that IS was responsible for the attack.

The official told AP that US intelligence agencies had collected information in recent weeks that IS was planning an attack in Moscow. The officer claimed US officials had privately shared the intelligence earlier this month with Russian counterparts.

ISIS-K is considered "one of the more successful branches" of the Islamic State, Daniel Byman, a counterterrorism and Middle East expert at CSIS, told Business Insider.

It was responsible for the suicide bombing at the Hamid Karzai International Airport in Kabul that killed 13 US military soldiers and 169 civilians in 2021.

ISIS-K's targeting of Russia could stem from several major historical conflicts that reflected the country's brutal treatment of Muslims. It is believed to have Russian-speaking Central Asians in its ranks.

"If you want, you can go back to the Russian conquest of the Caucasus," Byman said. "And then you could go to the Soviet deportations of Muslim populations" in the 1940s.

In a speech Tuesday, though, Putin had slammed the American warnings as "provocative," saying "these actions resemble outright blackmail and the intention to intimidate and destabilize our society."

On Friday, the UN Security Council condemned "the heinous and cowardly terrorist attack" and highlighted the need for those responsible to be held accountable. UN Secretary-General Antonio Guterres also condemned the terrorist attack "in the strongest possible terms," his spokesman said.