MOSCOW: Camouflage-clad gunmen opened fire at concertgoers with automatic weapons on Friday, killing at least 60 people and injuring 145 more in an attack claimed by Islamic State militants.

In the deadliest attack gunmen sprayed civilians with bullets just before Soviet-era rock group “Picnic” was to perform to a full house at the 6,200-seat the Crocus City Hall just west of Moscow.

Verified video showed people taking their seats in the hall, then rushing for the exits as repeated gunfire echoed above screams. Other video showed men shooting at groups of people. Some victims lay motionless in pools of blood.

Russian investigators said the death toll was more than 60. Health officials said about 145 people were wounded, of which about 60 were in critical condition.

In the 2004 Beslan school siege, Islamist militants took more than 1,000 people, including hundreds of children, hostage.

Russian President Vladimir Putin was being updated by security chiefs about the situation, including from Alexander Bortnikov, the head of the Federal Security Service (FSB), the Kremlin said.

Russian investigators published pictures of a Kalashnikov automatic weapon, vests with multiple spare magazines and bags of spent bullet casings.

Islamic State, the militant group that once sought control over swathes of Iraq and Syria, claimed responsibility for the attack, the group’s Amaq agency said on Telegram.

A grainy picture was published by some Russian media of two of the alleged attackers in a white car.

The fate of the attackers was unclear as firefighters battled a massive blaze and emergency services evacuated hundreds of people while parts of the venue’s roof collapsed.

Islamic State said its fighters attacked on the outskirts of Moscow, “killing and wounding hundreds and causing great destruction to the place before they withdrew to their bases safely.” The statement gave no further detail.

The United States has intelligence confirming Islamic State’s claim of responsibility for the shooting, a US official said on Friday. The official said Washington had warned Moscow in recent weeks of the possibility of an attack.

“We did warn the Russians appropriately,” said the official, speaking on condition of anonymity, without providing any additional details.