York Regional police have a section of Yonge Street in Richmond Hill blocked off Thursday morning, for a fatal hit and run investigation.

Police were called to the area between Stouffville Road and King Road after a man's body was found in the roadway around 3:30 a.m.

Police say they are now looking for a silver Mercedes SUV in connection with the collision, but believe other vehicles may have been involved.

In another twist, the province's Special Investigations Unit has been called in to investigate because the police vehicle that responded to the call may have made contact with the man's body.

The SIU is called in when police officers are involved in incidents where someone has been seriously injured, dies or alleges sexual assault.