Several hostage takers were killed during a special forces operation to free two prison guards held in Rostov, southern Russia, according to Russian media reports. The guards emerged unhurt after the storming of the pre-trial detention center.

The six detainees, who were facing terrorism charges related to the Islamic State (IS) group, were reportedly armed with knives. They had demanded a vehicle, firearms, and free passage out of the facility.

Authorities responded swiftly after reports of the hostage situation emerged on Sunday morning. In a video released by the prisoners, one of the hostages mentioned that the detainees had “serious intentions.” The detainees claimed to be IS members and insisted that their actions were premeditated.

Reports indicate that the detainees had smuggled knives, IS flags, and mobile phones into their cells. They managed to break the bars of a cell window, gain access to a guard room, and seize the hostages.

The operation highlights the ongoing threat posed by IS within Russia. Several IS-linked attacks have occurred on Russian soil, the most recent in March when gunmen attacked a concert hall in Moscow, resulting in 145 deaths and over 500 injuries. Russia attempted to link that attack to Ukraine, but Kyiv promptly denied any involvement.