After the horrific Moscow attack, Russian President Vladimir Putin called it a "barbaric terrorist act". While addressing the nation, Putin said that the four gunmen responsible for the attack had been arrested. 

"Our enemies will not divide us," he said. 

A day of mourning was declared on Sunday after the tragic incident. 

The Russian president added that the attackers tried to escape towards Ukraine after the incident and the security has been tightened in response.

Vladimir Putin has thanked emergency services and special services for their efforts after last night's attack in Moscow.

All those responsible will be punished, the president added. “All perpetrators, organisers and customers of this crime will suffer fair and inevitable punishment. Whoever they are, whoever guides them. I repeat, we will identify and punish everyone who stands behind the terrorists, who prepared this atrocity, this attack on Russia, on our people,” Putin said.

He also said that the Federal Security Service of Russia and other law enforcement agencies are working to identify and uncover the entire accomplice base of terrorists: those who provided them with transport, outlined escape routes from the crime scene, prepared caches, caches of weapons and ammunition.

Meanwhile, at least 143 people were killed after a group of armed men stormed into Crocus City Hall concert venue in Moscow, opened fire, and detonated explosives. 

According to the Kremlin, at least 11 people were detained in connection with the incident. 

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