Barbaric terrorist act…In his address to the nation, Putin declared March 24 as a day of mourning.

Russian President Vladimir Putin on Saturday called the Moscow concert hall attack, which took 143 lives, a “barbaric terrorist act.” He has also announced one day mourning in the country on March 24. I am speaking to you today in connection with a bloody, barbaric terrorist act that claimed the lives of dozens of innocent, peaceful people. Addressing the nation on television, the Russian President said that I declare March 24 a national day of mourning.

At least 143 people were killed when a group of armed men stormed the Crocus City Hall concert venue in Moscow, opening fire and detonating explosives. Several videos circulated on social media showed clouds of smoke and flames rising from the venue. Russian authorities have arrested 11 people, including four suspected gunmen, in connection with the shooting, according to the Kremlin, Reuters reports.

Although the Islamic State (ISIS) has claimed responsibility for the major attack, it has not provided any evidence to support the claim. It is considered to be the worst terrorist attack in Russia in the last two decades. The head of the Federal Security Service told President Vladimir Putin on Saturday that four of the 11 detained were directly involved in the attack, according to Russia’s state news agency Tass.