A woman mourns at a makeshift memorial in front of the Crocus City Hall on Saturday, a day after a gun attack in Krasnogorsk, outside Moscow, killed at least 133 people. Olga Maltseva/AFP via Getty Images hide caption A woman mourns at a makeshift memorial in front of the Crocus City Hall on Saturday, a day after a gun attack in Krasnogorsk, outside Moscow, killed at least 133 people. The death toll from a mass
shooting at a concert hall on the outskirts of
Moscow Friday evening has risen to at least 133 people, as emergency responders continued to clear away the rubble. At least another 145 others were reported injured. Russia's Investigative Committee, which released the number of casualties, said they expect the number of victims to continue to rise. In his first televised address to the nation since the attacks took place,
Russian President
Vladimir Putin said Saturday afternoon that the
Kremlin had arrested all four assailants directly involved in the shooting as well as seven others with suspected ties to the attack. "All the perpetrators, organizers and those who ordered this crime will be justly and inevitably punished," Putin said. "We will identify and punish everyone who stands behind the terrorists who prepared this atrocity, this strike against
Russia, against our people." Russia's interior minister said Saturday that all four suspected attackers are foreign citizens. A U.S. official confirmed to NPR that the U.S. believes an
Islamic State affiliate group known as Islamic State Khorasan Province, or ISIS-K, was responsible for the attack. The group, based in eastern
Afghanistan, claimed responsibility for the attack on its Telegram channel late Friday. Members of emergency services work at the scene of the gun attack at the Crocus City Hall concert hall in Krasnogorsk, outside Moscow, on Saturday. Stringer/AFP via Getty Images hide caption Members of emergency services work at the scene of the gun attack at the Crocus City Hall concert hall in Krasnogorsk, outside Moscow, on Saturday. U.S. intelligence officials also said they had warned the Kremlin earlier this month about a possible attack based on intelligence information. "The U.S. Government had information about a planned terrorist attack in Moscow - potentially targeting large gatherings, to include concerts," Adrienne Watson, a spokesperson for the National Security Council, said in a statement. Watson said the intelligence prompted the U.S. Embassy to issue a security advisory to Americans living in Russia, and share the information with Russian authorities in accordance with its longstanding "duty to warn" policy. In his remarks on Saturday, Putin made no mention of ISIS-K, instead accusing Ukrainian authorities of trying to help the four assailants escape via Ukraine. "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," Putin said. Russian investigators said the assailants were detained in the western Bryansk region, not far from the border with Ukraine. Ukrainian officials have denied any involvement, with Ukraine's foreign ministry accusing Russian authorities of using the deadly assault to try to rally support for the Kremlin's war in Ukraine. The attack began late Friday after camouflaged gunmen carrying automatic assault rifles burst into the Crocus City Hall — a large shopping and entertainment center on the western outskirts of Moscow. Concertgoers had gathered at the venue to see the veteran Russian rock band Piknik. Harrowing video footage shows the men firing at bystanders as they attempted to hide or rush for the emergency exits. Some witnesses reported seeing the assailants pour a liquid on the concert hall's seating and curtains before setting it on
fire. Additional footage released by Russian authorities shows the charred seating and debris from inside the venue.