Hours after a terrorist attack on a concert hall near Moscow, Russia said on Saturday that it had arrested 11 people, including four assailants, and reported a new death toll of 93, which it warned could rise.

Friday evening’s attack, which was claimed by the Islamic State, is the deadliest in Moscow for at least a decade.

The Kremlin said the head of the FSB security service had informed President Vladimir Putin about the arrests on Saturday.

“FSB Director Alexander Bortnikov reported to the president the detention of 11 people, including four terrorists involved in the terrorist attack at Crocus City Hall,” it said in a statement.

Russia’s Investigative Committee, which probes major crimes, said on Saturday that at least 93 people had been killed.

“At the moment, it has been established that 93 people are dead. The death toll is expected to rise,” it said in a statement published on Telegram.

It said people died both from gunshot wounds and from smoke inhalation after a fire engulfed the packed venue in Moscow’s northern Krasnogorsk suburb.