Four prison employees have been killed after prisoners staged a revolt in a Russian penal colony and took hostages, federal authorities say.

Special forces stormed the IK-19 Surovikino facility in the southwestern Volgograd region after knife-wielding prisoners, who identified themselves as Islamic State (IS) militants, claimed to have taken control of the sprawling complex.

Authorities said the special forces operation had freed some hostages and neutralised all the attackers, but later confirmed that four prison employees had died.

An unverified image posted on social media appeared to show an inmate holding a knife standing above a bloodied prison guard during the revolt.

Russias Rosgvardia National Guard said snipers shot four attackers in the rescue operation.

Heavily armed troops were filmed arriving at the prison in footage posted to the Telegram messaging app by the National Guard.

The attack began during a disciplinary commission meeting, Russias Federal Penitentiary Service (FSIN) said in a statement. The attackers were said to have slashed guards and wounded several prison staff.

The FSIN said eight prison employees and four convicts had been taken hostage. Some reports in Russian media suggested that the prisons director and deputy director were among those seized.

The criminals inflicted stab wounds of varying severity on four employees, three of whom died. Another four who resisted were hospitalised, one of whom died in the hospital.

Russian media named the attackers as Ramzidin Toshev, 28, Rustamchon Navruzi, 23, Nazirchon Toshov, 28, and Temur Khusinov, 29. All were natives of Uzbekistan and Tajikistan.

In dramatic mobile phone footage released by the attackers, they identified themselves as IS militants. The men said they were motivated by the desire to avenge the persecution of Muslims.

The video also showed prison officials lying in pools of blood, while in separate clips the attackers roamed the prison courtyard.

Volgograd regional governor Andrei Bocharov said earlier that the hostage-taking posed no threat to the civilian population.

President Vladimir Putin was filmed taking part in a virtual meeting with security chiefs, during which the Kremlin said he had been updated on the situation.

The Volgograd hostage-taking is the second such incident this summer, after six prisoners who pledged allegiance to the Islamic State group captured two guards at a facility in the neighbouring Rostov region.

Five of the prisoners were killed and a sixth sentenced to 20 years in prison following the attack.

Prosecutors said they had opened a case relating to a hostage-taking.

IK-19 Surovikino is a high-security penal colony. It is believed to hold about 1,200 inmates. (BBC)