Four prison officers were killed in a high-security Russian prison after inmates, who identified as members of the terrorist group Daesh, took several staff members hostage.

The incident occurred at the penal colony in Surovikino, where Russian special forces intervened, resulting in the deaths of the hostage-takers and the rescue of the remaining hostages. The Russian National Guard revealed that snipers from their special forces neutralized the four attackers with precise shots, according to CNN.

Footage circulated online showed three officers in uniform lying motionless in pools of blood, with one having a slashed throat. A fourth officer was found kneeling at the entrance.

Additional footage verified by CNN showed the hostage-takers raising an Daesh flag on the western edge of the facility. One of the attackers was seen standing over a bloodied man in a Russian Federal Penitentiary Service uniform.

While the exact motives of the attackers remain unconfirmed, the SITE terrorism monitoring group reported that one suspect described the assault as "revenge" for a recent attack on a concert near Moscow that killed over 130 people.