The terrorists used a highly flammable liquid to set on fire the premises of Crocus City Hall, a popular music venue outside Moscow, and also used automatic firearms, the Russian Investigative Committee said, Paralel.Az reports citing TASS.

"It has been confirmed that the terrorists used a highly flammable liquid to set on fire the premises of the concert hall with spectators, including the wounded people," the IC’s press service said.

The preliminary investigation data suggests that the terrorists used automatic firearms during the attack, which have been discovered and seized.

The terrorist attack took place at the Crocus City Hall in the town of Krasnogorsk outside Moscow late on March 22. Unidentified gunmen armed with automatic weapons went on a shooting spree. According to the latest data from Russia’s Investigative Committee, more than 90 people were killed but that number may grow. According to the Moscow Region’s Health Ministry, three children are among those dead. Some 121 people were rushed to hospitals.

The Federal Security Service (FSB) has announced the detention of 11 people involved in the attack, including four perpetrators.