Russian President Vladimir Putin on Saturday vowed to punish those behind a "barbaric terrorist attack" on a Moscow concert hall that killed more than 130, saying Russia had arrested four gunmen who were trying to flee to Ukraine.

Kyiv has strongly denied any connection, and Putin made no reference to claims of responsibility by the Islamic State group (IS) in his first public remarks on the attack.

At least 133 people were killed when camouflaged gunmen stormed the Crocus City Hall, in Moscow's northern suburb of Krasnogorsk, and then set fire to the building on Friday evening.

The jihadist group has claimed the attack, writing on a Telegram channel that it was "carried out by four IS fighters armed with machine guns, a pistol, knives and firebombs," as part of "the raging war" with "countries fighting Islam".

Russian officials expect the death toll to rise further, with more than 100 injured in hospital.

"Terrorists, murderers, non-humans ... have only one unenviable fate: retribution and oblivion," Putin said in a televised address to the nation.

Calling the attack a "barbaric, terrorist act", he said "all four direct perpetrators ... all those who shot and killed people, have been found and detained".

"They tried to escape and were travelling towards Ukraine, where, according to preliminary data, a window was prepared for them on the Ukrainian side to cross the state border," he added.

He named Sunday a day of national mourning.

Russia arrested 11 people in connection with the attack on Saturday, the FSB security service said.

Kyiv, facing a Russian military offensive for the past two years, had "nothing to do" with the attack, presidential aide Mykhailo Podolyak said in a statement.

Some 107 people were still in hospital, many in a critical condition, Deputy Prime Minister Tatyana Golikova said.

Investigators said people died both from gunshot wounds and smoke inhalation after a fire engulfed the 6,000-seater venue.

The head of the state-run RT media outlet, Margarita Simonyan posted two videos claiming to be interrogations of two handcuffed suspects, who both admitted to the attack but did not say who organised it.

The interior ministry said all four of the suspected gunmen were from Tajikistan, a country that borders Afghanistan and where the jihadist group is active.

In Moscow, residents stood in long lines in the rain to donate blood for those hospitalised, and mourners came to lay flowers outside the concert hall.

Major events were cancelled across the country.

Statements of condemnation from world leaders continued to roll in.

Russia's powerful intelligence services were also in the spotlight in the wake of the attack.

Just three days earlier, Putin had publicly dismissed a US warning of an "imminent" attack in Moscow as propaganda designed to scare Russian citizens.

The US embassy in Russia had warned on 7 March that "extremists have imminent plans to target large gatherings in Moscow, to include concerts".

Washington said after the attack it had also shared details directly with Moscow.

But speaking to FSB chiefs last Tuesday, Putin had called it a "provocative" statement and "outright blackmail... to intimidate and destabilise our society".
Related Story