Ontario’s police watchdog has launched an investigation after a teenager was seriously hurt in a crash in Hamilton early Saturday.

The Special Investigations Unit reported that two Hamilton police officers were patrolling near Centennial Parkway North and Delawana Drive at about 2:30 a.m. when they observed two vehicles heading north at high speed. One vehicle left the area, while officers followed the second — a Kia Rio.

According to the SIU, the Kia was later involved in a multi-vehicle collision at the intersection of Centennial Parkway and South Service Road.

A 15-year-old passenger in the Rio was transported to hospital with serious injuries.

The SIU has assigned three investigators and one forensic investigator to examine the circumstances surrounding the incident.