VOLGOGRAD, August 23. /TASS/. Two of the four victims of a hostage-taking incident inside a high-security prison in southern Russia’s Volgograd Region are in critical conditions, Anatoly Sebelev, head of the region’s healthcare committee, said.

"Two are in critical conditions, the other two - in condition of medium gravity. Surgeries are being conducted at the regional hospital," he said in a video posted on the Telegram channel of the regional administration.

Several inmates at a maximum-security penal colony (IK-19) in the Volgograd Region have taken the facility’s staff hostage, the Russian Federal Penitentiary Service (FSIN) told TASS earlier. One penitentiary officer was been killed, and several more were injured.

A criminal probe has been launched. The FSIN has dispatched its central office employees to the scene for an investigation.