Vladimir Putin claims Moscow attackers caught 'trying to escape towards Ukraine'

At least 133 people have been killed and more than 140 injured when gunmen attacked a packed concert venue on the outskirts of Moscow, Russia has said.

A large fire engulfed the roof of the complex and dramatic video showed panicked concertgoers taking cover as shots and explosions rang out.

Russian President Vladimir Putin said all four gunmen have been arrested, and that the suspects were trying to flee to Ukraine - Kyiv said allegations of Ukrainian involvement are "absurd".

The US has said it's credible that the Islamic State group could be behind the attack, after the group said it did it. Russia has not commented on these claims.