UPDATE: SIU called in to investigate fatal crash in Pickering

Ontario's police watchdog has taken over the investigation into a fatal crash in Pickering Saturday morning. 

The Special Investigations Unit says two vehicles collided near Brock Road and Concession Road 5 at about 9 a.m., with reports that one of the vehicles burst into flames. 

Saturday afternoon, the SIU revealed more details, saying an OPP officer was doing speed enforcement on the 407 ETR at the time when he began to follow a car that was headed eastbound.

It then took the off ramp to Brock Road and headed southbound, when it struck a Purolator truck.

The driver of the car was pronounced dead at the scene, while the 36-year-old male driver of the truck was taken to Sunnybrook Hospital to be treated for serious injuries. 

Durham Police say they are also conducting an investigation into the collision. 

The SIU is called in for cases involving police in which someone is killed, injured or accused of sexual assault.

- With files from CP24