TORONTO -- The Special Investigations Unit (SIU) is investigating after a collision involving a Halton police cruiser left a person with serious injuries in Milton.

On Wednesday, a Halton Regional Police Service cruiser and another vehicle were involved in a crash in the area of Steeles Avenue and Cleve Court just before 9 p.m.

The civilian was transported to hospital with serious injuries, according to the SIU.

The officer involved was also injured but was not transported to hospital.

The cause of the collision is unknown.

Due to the circumstances of the collision, the SIU was notified and took over the investigation.

Five investigators, including one forensic investigator and one collision reconstructionist, have been assigned to the case.

Steeles Avenue East between James Snow Parkway and Fifth Line remains closed Thursday morning as the investigation continues.

Drivers are being asked to avoid the area.

Anyone with video evidence related to this incident is asked to upload it through the SIU website and anyone with information is asked to contact the lead investigator at 1-800-787-8529.

The SIU investigates incidents involving police officers that result in death, serious injury, sexual assault and/or the discharge of a firearm at a person.