The sister of the 21-year-old man shot and killed by police officers in North York says she believes he was unarmed at the time of the incident.

The Special Investigations Unit is investigating the deadly shooting, which took place near Leslie Street and Sheppard Avenue East around 12:30 a.m. on Monday.

man in 20s shot during police involved shooting

A 21-year-old man is dead following a shooting involving police overnight in Toronto. (Tony Smyth/CBC)

Officers were called to the area after someone reported two men fighting around 11 p.m. on Sunday, including one police tweeted was armed with a gun.

Melissa Wettlaufer said officers followed her brother, Alex Wettlaufer, into a park area. He was on the phone with his brother at the time, she said, asking him to get police to lower their weapons.

She said the officers told her brother to drop what he was holding.

"He told them it was just a phone, but they shot him anyway," she said.

The 21-year-old was rushed to hospital but died of his injuries around 8:30 a.m., the SIU said.

The SIU — an arms length agency that investigates when there has been a death, serious injury or allegations of sexual assault involving police — confirmed the incident took place in the park area and said officers from the Emergency Task Force and canine unit were involved in the search for the two men involved in the fight. 

The SIU said there was a confrontation involving police officers, a "police firearm was discharged" and "the man was struck."

Investigators have not said if the man was armed. 

Man shot was friends with Yatim

Melissa Wettlaufer said her brother is the second youngest sibling of 10 in their family, while she is the second-oldest and helped raise her brother. 

She also said Alex had gone to school with Sammy Yatim, the 18-year-old who was fatally shot by police on a TTC streetcar in 2013, and that the two were friends.  

Alex had been waiting to hear back about his application to join the military, Melissa Wettlaufer said.