MOSCOW, Russia (AFP)— Four men accused of involvement in the Moscow concert hall attack that killed at least 137 people were charged with terrorism Sunday and ordered to be detained pending trial.

All four risk a life sentence in prison, a statement from Moscow’s Basmanny district court said.

The men were ordered to be held until May 22, but that could be extended depending on when the date for their trial is fixed.

The court said two of the defendants had pleaded guilty, one of them, from Tajikistan, “entirely acknowledged his guilt”, said the statement.

Officials have already said the gunmen were all foreign nationals.

Russian officials say they have arrested 11 people in connection with Friday night’s attack at the Crocus City Hall in Moscow’s northern suburb of Krasnogorsk, including four of those who carried out the killings.

The court released footage showing three suspects being brought to a courtroom handcuffed and bent double by police officers. They were seated in a glass-fronted cell reserved for defendants.

A fourth man arrived in a wheelchair, his eyes closed.

One of the defendants had one of his ears bandaged, as in earlier videos of their arrest Saturday, when three of them had bloodied faces.

Although the Islamic State group has claimed responsibility for the attack, Russian President Vladimir Putin appeared to suggest Kyiv’s involvement when he said Saturday that they had been arrested while trying to flee to Ukraine.

Ukrainian President Volodymyr Zelensky and the United States have dismissed any suggestion Kyiv was involved.

The attack was the deadliest carried out in Russia since the beginning of the 2000s.