Inmates at a prison in Russia’s southern Volgograd region have attacked staff with knives and taken hostages, Telegram news channel Baza reported Friday.

Video footage of the incident, which took place at a penal colony in the town of Surovikino, showed prisoners holding knives, while multiple prison guards appeared lifeless. Baza said that three people had died during the attack, and several were wounded, while two others had managed to escape. The person filming the attack claimed to represent Islamic State.

The Federal Penitentiary Service (FSIN) has confirmed that one employee was killed, while Baza said the prison director Andrey Devyatov had been taken to intensive care.

FSIN said measures to free the hostages were already underway. Telegram news channel SHOT said that the facility held a total of 1,230 prisoners.

At least three prisoners are known to have organised the attack, according to state-owned news agency TASS. The hostage-takers have demanded $2 million and a helicopter, North Caucasus news outlet Sapa Kavkaz said, while the attack took place during a meeting of the prison’s disciplinary commission, according to state-owned news agency RIA Novosti.

This is a developing story.