MOSCOW (AP) Russian authorities arrested the four men suspected of carrying out the attack on a suburban Moscow concert hall that killed at least 133 people, President Vladimir Putin said Saturday during an address to the nation. He claimed they were captured while fleeing to Ukraine.

Kyiv strongly denied any involvement in Fridays attack on the Crocus City Hall music venue in Krasnogorsk, and the Islamic States Afghanistan affiliate claimed responsibility.

Putin didnt mention IS in his speech, and Kyiv accused him and other Russian politicians of falsely linking Ukraine to the assault in order to stoke fervor in Russias war in Ukraine, which recently entered its third year .

A U.S. intelligence official told The Associated Press that U.S. agencies had confirmed that IS was responsible for the assault and that they had previously warned Moscow an attack could be imminent.

Putin said authorities have detained a total of 11 people in the attack, which also injured more than 100 concertgoers and left the venue a smoldering ruin. He called it a bloody, barbaric terrorist act and said Russian authorities captured the four suspected gunmen as they were trying to escape to Ukraine through a window prepared for them on the Ukrainian side of the border.

Russian media broadcast videos that apparently showed the detention and interrogation of the suspects, including one who told the cameras he was approached by an unidentified assistant to an Islamic preacher via a messaging app channel and paid to take part in the raid.