Assailants stormed into a large concert hall in Moscow and sprayed the crowd with gunfire, killing over 60 people, injuring more than 100, and setting fire to the venue in a brazen attack on Friday, news agency AP reported.
It is to be noted that the attack comes just days after President Vladimir Putin secured his hold on power in a highly orchestrated electoral landslide.
According to AP, the Islamic State group has claimed responsibility for the attack in a statement released through affiliated social media channels. The group's branch in Afghanistan was planning an attack in Moscow, and the information was shared with Russian officials, AP reported citing a US intelligence official.
It was unclear what happened to the attackers following the raid, which state investigators were looking into as terrorism, the report said.
The attack, which left the concert hall in flames with a collapsing roof, was Russia's deadliest in years, and occurred as the country's war in Ukraine entered its third year.
According to AP, Moscow Mayor Sergei Sobyanin described the raid as a "huge tragedy".
As per the AP report, the Kremlin said Putin was informed minutes after the assailants stormed Crocus City Hall, a large music venue on Moscow's western outskirts that can seat 6,200 people.
Reports suggest that the attack occurred as people gathered for a performance by the Russian rock band Picnic. The Investigative Committee, the state's top criminal investigation agency, announced early Saturday that more than 60 people had been killed.
Health officials released a list of 145 injured, with 115 of them hospitalised, including five children, AP reported.
According to some Russian news reports, the fire that broke out after the assailants threw explosives may have trapped more victims.
The purported visuals on social media showed the building on fire, with a massive cloud of smoke rising into the night sky. The street was illuminated by the blinking blue lights of dozens of firetrucks, ambulances, and other emergency vehicles, while fire helicopters buzzed overhead to drop water on the blaze, which took hours to extinguish.