A man shot at a baseball field in Manitoba on Sunday had already surrendered to police when they opened fire, Norway House First Nation chief Ron Evans says.

"He was unarmed, he had his hands up," Evans told CTV News on Monday. "No one can understand why the RCMP member had to pull the trigger four times."

Alberta's Serious Incident Response Team has been tasked with investigating an alleged shooting incident that played out in front of nearly 300 baseball spectators at the Norway House First Nation on Sunday. Police allegedly chased a local man onto the baseball field and fired four shots at him. The victim, Evan M. Cromarty, was struck in the shoulder by a bullet, witnesses said. He was then airlifted to hospital with non-life threatening injuries.

Cromarty had allegedly been fleeing police when he ran onto the field. Umpires stopped the game and told spectators to look away as the confrontation played out.

The province announced the ASIRT investigation in a brief statement on Monday.

Among the spectators at the game was Evan Cromarty's cousin, Purvis Cromarty, who recognized his relative immediately. After RCMP opened fire, Purvis thought his cousin Evan was dead.

"That's when my heart started pounding, once I see the shots fired, I just turned away and put my head against the fence and shed a few tears, because I thought he was gone," he said.

Chief Evans said the community has been traumatized by the shooting, and it will take time for people to recover. Evans said he spoke to Manitoba Premier Greg Selinger on the phone and has the premier's assurance that a full, independent investigation will be carried out.

Many spectators at the field were parents with young children, including Skylar Tait-Reaume, who was at the baseball diamond to watch a game with his three-year-old son.

"For my son to see that at that age, that's something I'd never seen when I was that age," he told CTV News on Monday. "I still get the chills just sitting here right now, thinking about what happened."

With files from The Canadian Press and CTV Winnipeg