Ontario's Special Investigations Unit is investigating after a SUV being pursued by Toronto Police crashed into an Uber vehicle early Sunday, sending eight people to hospital.

Police officers tried to stop a black Acura SUV near York Street and Bremner Boulevard shortly before 3 a.m., said SIU spokesman Jason Gennaro. The vehicle fled and "there was a pursuit," he said.

Three blocks away, the Acura collided with a Chevrolet Malibu, which was operating as an Uber vehicle, at the intersection of Bay Street and Wellington Street West.

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The collision sent eight people to hospital, at least three of them with serious injuries. Mr. Gennaro said investigators are determining how many people were in each vehicle. No pedestrians or police officers were injured.

One person was arrested at the scene. Constable Allyson Douglas-Cook said Toronto Police could not provide information on charges because the SIU has invoked its mandate. The civilian agency investigates deaths or serious injuries involving police.

Mr. Gennaro said he could not comment on the reason police initially attempted to pull over the Acura, saying it is part of the investigation.

The SIU is appealing for any witnesses to contact investigators. The agency has assigned eight investigators, two forensic investigators and a traffic reconstruction expert to probe the incident.