The Special Investigations unit has been called in after a 33-year-old was shot and killed by Windsor police Wednesday morning.

Police say there was an altercation in the alley between the Shoppers Drug Mart and McDonald's restaurant near Goyeau Street and Tuscarora Street.

Two officers received non-life threatening injuries during the altercation.

Police closed off a section of Goyeau and Tuscarora around 8 a.m. and it remained taped off all day.

At a news conference Wednesday afternoon Windsor police say all questions should now be directed to the SIU, which is an arm’s length agency that investigates reports involving police where there has been death, serious injury or allegations of sexual assault.

The SIU said six investigators and four forensic officers are involved in the probe.

Witnesses to the events say they heard several gunshots in the area.

A woman named Maureena told AM800 News everything she saw at the scene is replaying in her mind.

"There was a guy that had a butcher block with some knives in it. The police told him to stop; he didn't. He took out one of the knives in the butcher block and went to attack the officers. They pulled out their tasers. That didn't work and then the other officers shot him."

One woman said her son was working at the McDonalds restaurant in the area when he saw cops chasing a man who turned around and went after an officer.

The woman gave a similar account to Maureena's, saying an officer tried to taser the man, but it didn’t have any effect and a man “knocked the cop to the ground gets up, goes after another cop, and that is when officers opened fire."

Windsor police said the incident started with a 911 call at 8:05 a.m.

"Patrol officers were dispatched to a complaint, in the area of Ouellette and University," said Deputy Chief Vince Power.

He said officers found a man matching the description they were looking for at Goyeau and Wyandotte.

"Officers interacted with the male. During the interaction, police fired their issued pistol."

The man was taken to hospital where he was pronounced dead at 9:29 a.m.

The SIU is now asking any witnesses to come forward with information, and people who might have video of this shooting is asked to upload them on the agency website.

The victim's name has not been released, but CTV News has been told the man’s family has been notified and an autopsy will be done in London on Thursday.