EDMONTON -- Mounties who opened fire on a Sherwood Park man armed with a revolver-style pellet gun, seriously injuring him, were reasonable in their use of force in the 2018 shooting, according to Alberta's police watchdog.

Strathcona County RCMP were called to a home in Sherwood Park in the early morning hours of March 4, 2018, the Alberta Serious Incident Response Team said in its report, released Wednesday.

A 40-year-old man called 911 saying he was having hallucinations and that he had stabbed himself in the neck multiple times.

Three Mounties entered the home after identifying themselves to a woman living there who said she wasn't aware a man in the basement had called for an ambulance,

The officers were then let into the dark basement, where they could hear a man talking indistinctly. When they shined their flashlights on him standing at the end of a hallway, the man was bleeding "significantly from the neck" and armed with what appeared to be a revolver at his side, according to ASIRT.

Police yelled at the man to drop the weapon, but when he began to advance on them and raised the gun to nearly chest level, they shot him.

Despite suffering multiple gunshot wounds, the man kept walking toward the officers with his gun raised and police once again opened fire until he fell to the ground, ASIRT said.

The man then surrendered, was handcuffed and paramedics waiting outside treated him and rushed him to hospital.

It was later determined the man suffered gunshot wounds to his torso, groin and leg and had also given himself an eight-centimetre laceration to the neck.

The man was not under the influence of drugs or alcohol, the report found.

Investigators later determined the firearm involved was a Crosman 357 revolver-style pellet gun and also found two knives, a bloody towel and a handwritten note addressed to the woman living in the home.

"The note advised her that he did not wish to kill himself, but indicated that he had been having hallucinations for weeks," said ASIRT. The man also denied he was suicidal "although there were signs to the contrary."

ASIRT's report concluded that the officers involved were dealing with an armed man who was not complying with repeated commands. When he advanced on them, they faced a risk of bodily harm or death and were not required to wait and see if the man would open fire on them first, it found.

"If the person acting unlawfully objectively appears to be pointing a gun and to have the immediate ability to use it, officers are lawfully entitled to respond with lethal force," ASIRT wrote. "In considering all of the circumstances of this matter, it is the opinion of executive director Susan Hughson, Q.C. that the evidence does not provide reasonable grounds, nor even reasonable suspicion, to believe that any of the three officers committed a Criminal Code offence."

ASIRT, formed in 2008, is a civilian oversight body whose aim is to independently investigate all use-of-force incidents in Alberta that result in serious injury or death.