Prisoners at a pre-trial detention centre in Russia's southern region of Rostov took two employees hostage, the Federal Penitentiary Service said on Sunday.
"The institution operates as usual, the situation is under control," the service said in message on the Telegram messaging app.
It added that law enforcement agencies were called on site.
Baza, a Telegram channel with links to Russian law enforcement, said that six of detainees were involved in taking the employees hostage, among them several already convicted of terrorism charges.
Reuters could not independently verify the Baza report.
