Ontario’s police watchdog is investigating an early morning crash that occurred after a police pursuit in Oshawa.

According to the Special Investigation’s Unit, Durham Regional Police officers were in the Dundas Street and Thickson Road area at around 1 a.m. when, for reasons unknown, they attempted to pull over a vehicle.

The vehicle continued to drive a short distance before colliding with a tree near King Street West and Thornton Road.

The SIU says the 26-year-old driver suffered “a serious injury” and was transported by paramedics to Oshawa General Hospital, where he remains.

A CTV News Toronto photojournalist at the scene said the vehicle crashed near the fence of Union Cemetery and sustained significant front-end damage.

The intersection was completely closed off to traffic for several hours while police and SIU investigators took photographs and reconstructed the crash.

The SIU is an arm’s length agency which is called in to investigate whenever police are involved in a death, serious injury or allegations of sexual assault.

They’ve assigned forensic investigators and a collision reconstruction officer to the case.

The agency is asking anyone who witnessed the crash or has any information about the incident to contact them.