BARRIE, ONT. -- Ontario's Special Investigations Unit (SIU) is investigating a confrontation between police officers and an armed man in Collingwood on Wednesday that ended with the man being fatally shot.

Ontario's watchdog says police initially responded to reports of an armed man barricaded in a home.

Investigators say that as officers were setting up a perimeter on Third Street near Beech Street, the man came out with the gun in his hand, and an officer zapped him with a Taser. They say it didn't stop the man who kept walking when the same officer shot him.

An eyewitness says the man refused to listen to police.

"The cop told him to drop the eff'in gun, and the kid said F-U and continued to walk up the sidewalk, and the officer shot," she pauses, visibly upset. "Oh my god. I'm sorry, I was just standing so close."

The shooting happened shortly before the noon hour in a residential area near downtown.

Paramedics performed extraordinary measures to try and save the 29-year-old's life, but his injuries were too severe. He was pronounced dead in the hospital.

The deceased has not been identified.

The SIU is an independent civilian agency that investigates reports involving police where there has been death, serious injury or allegations of sexual assault.