A motorcycle collision that sent a rider to hospital Wednesday afternoon is being probed by Ontario's Special Investigations Unit.

Police say the motorcyclist is in serious condition with a head injury after a crash around 12:35 p.m. at Kipling and Evans avenues.

A Toronto police spokesperson said a traffic officer was involved an "interaction" with the motorcyclist prior to the collision.

The SIU is called in cases in which police are involved in a serious injury or death, or when allegations of sexual assault are raised.