After a hostage crisis at Volgograd Region Prison, police "neutralize" 4 prisoners

Snipers from Russia's National Guard murdered four detainees on Friday after they attacked four prison guards and briefly held others hostage while declaring allegiance to the Islamic State organization, according to officials.

According to the Federal Prison Service, four prisoners held captive eight prison officers and four other inmates. According to reports, they stabbed four guards, three of whom died on the spot and the fourth died later in the hospital. According to the organization, three other guards were hospitalized due to injuries.

Russia's National Guard claimed that its snipers "neutralized" all four attackers, releasing all captives, while the Federal Prison Service also claimed credit for the perpetrators' deaths. The disparity could not be explained immediately.

After an hours-long siege, Russian special forces stormed the IK-19 Surovikino prison colony in southern Volgograd and killed all four attackers.

Three uniformed jail staff members were found unconscious in pools of blood, one with his throat slit, according to graphic social media footage. A fourth member of staff can be seen on his knees in a doorway.

In another video, the purported hostage takers are seen brandishing ISIS flags.

In the recordings, the alleged attackers professed to support the Islamic State group as well as the suspects apprehended in the March terrorist attack on a Moscow music hall that killed 145 people. An ISIS offshoot claimed responsibility for the attack, in which gunmen killed patrons who were waiting for a prominent singing group to play and set fire to the venue.

Russian President Vladimir Putin said Friday that the chief of the Federal Penitentiary Service informed him of the situation in the Volgograd colony.

The incident followed another hostage crisis in Russia in June, when six detainees held two staff of a pre-trial detention center in the southern Russian city of Rostov-on-Don hostage for many hours before being liberated.

The captives had connections to ISIS and were slain during the operation.