The shooting was caught on video that was shown at Percy Davis's trial on Tuesday. ((Edmonton Police Service))

An Edmonton police officer told a judge on Tuesday he feared for his own life, and the lives of others, when he shot a young man in the neck and chest 2½ years ago.

Const. Myles Stromner was called to Abbotsfield Mall on Aug. 8, 2008, to check reports that a young man was carrying a butcher knife.

Stromner testified he was sitting in his patrol car when Percy Davis leaned in, with the knife raised over his head. His call to the police dispatcher was played in court.

"I got the kid with the knife," Stromner is heard saying. "He's challenging me right now. I need cars here quick."

Davis is on trial in Edmonton Court of Queen's Bench on charges of assaulting a peace officer and possession of a dangerous weapon.

Stromner told court he pulled out his gun, but Davis didn't react and just walked away.  Stromner said he yelled at Davis and ordered him to drop the knife. He tried using pepper spray, but it had no effect.

Stromner decided to fire at Davis as soon as he got close to a nearby McDonald's restaurant. Davis was struck in the neck and chest.

"Control — we need an ambulance here now! Shots fired!" Stromner was heard shouting on the tape.  

Davis dropped the knife when Stromner aimed the gun at his head, court was told.

Stromner will be cross-examined Wednesday morning.

In July 2009, Stromner was cleared of all wrongdoing after the Alberta Serious Incident Response Team found that his actions in this incident were justified.