The Special Investigations Unit will look into the collision, which happened around 12:30 p.m. near the Woodbine Shopping Centre, at Rexdale Boulevard and Highway 27.
Investigators were talking to witnesses Saturday afternoon. Dozens of police and SIU vehicles are near the scene of the collision, CBC's Charlsie Agro said.
The SIU investigates deaths or serious injuries that involve police. It has assigned six investigators, a collision reconstruction expert and three forensic investigators.
A witness on scene told Agro that the procession had been heading north on Highway 27. He saw a police officer giving a woman CPR, but she was not responding. The same witness also said some people involved in the funeral procession were taken away on a paramedic bus.
Some people in the procession were kept from the funeral because their cars were being held by the SIU.