Ontario's police watchdog has eight people probing the circumstances surrounding a collision that left a woman on a bicycle with serious injuries in downtown Toronto.

The Special Investigations Unit issued a news release on Thursday about what is known about a series of events that occurred in Toronto's Queen Street West and Augusta Avenue area the day before.

According to the SIU, it is believed that at approximately 4:30 p.m. on Wednesday, Toronto police attempted to pull over a silver Infiniti that was driving north on Bathurst Street.

The vehicle was stopped just south of Queen Street.

When officers approached the vehicle on foot, the Infiniti turned east on Queen Street West, but was subsequently struck by another civilian vehicle, several blocks away, at Augusta Avenue.

The Infiniti then lost control and struck a woman on a bicycle, the SIU news release says.

The SIU says the 22-year-old cyclist suffered a broken leg and was treated at St. Michael's Hospital.

The Infiniti driver fled the scene after the cyclist was struck, but was soon arrested. He was treated for a jaw injury, the SIU says.

A person in the other vehicle suffered a shoulder injury.

A large stretch of Queen Street West remained closed for hours on Wednesday evening following the crash.

The investigation continues.

The SIU investigates reports involving police in which death or serious injury have occurred, or when allegations of sexual assault have been raised.

With a report from the CBC's Charlsie Agro