Head of Ukraine's Prosecutor General's Office (PGO) Yuriy Lutsenko has said the first to fire in the tragedy, in which five law-enforcement officers were killed, in Kniazhychi (Kyiv region) was an employee of the State Guard Service, who let off a warning shot.

"We see in this video that the first to fire was a State Guard Service employee, who was located behind the stone wall facing the scene of the shooting," Lutsenko said during a 1plus1 TV Channel show aired on Sunday.

According to Lutsenko, the State Guard Service employee fired in the air. A gun battle ensued between employees of Ukrainian law-enforcement agencies.

Lutsenko said there is a possibility that the house in Kniazhychi, which robbers were trying to vandalize, may have been raided for a second time – State Guard Service employees may have removed an elite auto from the premises.

As earlier reported, during the special operation of the National Police of Ukraine and the Immediate Reaction Force KORD to detain vandals in Kniazhychi during the morning of December 4, a firefight broke out between members of different police units.

Lutsenko said PGO investigators are looking into the actions of police commanders, who are suspected of dereliction of duty leading to especially serious consequences. He said actions taken by police SWAT officers at the scene were inappropriate.

Interior Minister of Ukraine Arsen Avakov said eight policemen were fired as a result of the incident and 12 more disciplined.