The province's Special Investigations Unit (SIU) has been called in after what Peel Regional Police are describing as "multiple shootings" on Highway 410 in Brampton early Monday.
The shootings left one person dead and another seriously injured.
Police were called to Highway 410 near Sandalwood Parkway at about 2:30 a.m. for a person who was shot.
When officers arrived, they located two people and a vehicle on the northbound lanes of Highway 410, said Const. Heather Cannon.
She said one person with gunshot wounds was transported to a trauma centre with serious injuries, while a second person, who was also shot, was pronounced dead.
While on scene, officers had an "interaction" with a separate vehicle, and due to that interaction the SIU was notified, Cannon said.
6 SIU investigators assigned to case
SIU spokesperson Monica Hudon said when officers arrived at the scene, the driver of an Audi SUV attempted to drive off and police tried to block it from moving forward.
"When they did so, the Audi reversed and at that time one officer discharged his firearm multiple times at the Audi," Hudon said.
"The Audi managed to reverse and then moved forward travelling northbound on Highway 410."
Hudon said the vehicle was later located abandoned on nearby Checkerberry Crescent.
"The SIU has three investigators and three forensic investigators assigned to this case," Hudon said.
The people in the Audi have not yet been found, and Hudon said investigators do not know if anyone in the vehicle was hurt.
Investigators are asking anyone who may have information to contact 1-800-787-8529.
Police closed down Highway 410 in both directions in the area for the investigation but all lanes have since been reopened.
The SIU is arms-length agency investigates reports involving police where there has been death, serious injury or allegations of sexual assault.