An 18-year-old man sustained "life-altering injuries" after being shot while out riding his bike Saturday evening.

The man was shot in the area of Roy Avenue and Cecil Street, in the Weston neighbourhood, at around 7:20 p.m., while he was out riding his bicycle with two relatives.

He was confronted by four people who drove in front of the cyclists, blocking their path, police said.

The two groups did not know each other.

One of the people in the vehicle pulled out a gun, and the group on bikes tried to flee, but the 18-year-old fell.

He was then shot, sustaining serious injuries. He was taken to hospital in critical condition, but has since been upgraded to stable, said Const. Rob Carver during a news conference on Tuesday.

A suspect vehicle was located a short time later in the area of Logan Avenue and Arlington Street.

The driver tried to flee but crashed on Elgin Avenue.

Three men and a woman were arrested and a sawed-off shotgun was seized.

Police believe the four suspects have gang ties, but the man who was shot did not.

Two of the men are charged with aggravated assault, and all four are charged with robbery with a firearm and numerous other firearm charges.

One of the men also is charged with 28 counts of theft under $5,000 in connection with thefts from 28 liquor outlets throughout the city.