Six detainees, some with links to Islamic State, took guards hostage at a pre-trial detention center in Russia’s southern region of Rostov and demanded free passage to negotiate with authorities, Russian media reported on Sunday.

According to the Baja Telegram channel, the men, some of whom have already been convicted of terrorism offences, broke the window bars of their cell and entered the guard room, where they took at least two prison officers hostage.

State media said some of the prisoners were accused of terrorist offences, including affiliation with the Islamic State group, which claimed responsibility for a deadly attack on a Moscow concert hall in March.

Russia’s Federal Penitentiary Service said two employees of a pre-trial detention center in Rostov were taken hostage.

“The institution is operating normally, the situation is under control,” the service said on the Telegram messaging app.

It also said that law enforcement agencies are present at the spot.

Pictures from the scene showed roads around the detention center closed.

The prisoners had demanded cars and free travel, the Interfax news agency said.