Officers responded just before 4 p.m. on Oct. 5 to the Franceschini Bridge, located over Highway 410 between Williams Parkway and Bovaird Drive.
Investigators said a man was seen throwing large rocks off the bridge, which led to a motor vehicle being hit.
They said it caused a motor vehicle collision and extensive damage to the vehicle.
Police said the suspect is described as a man wearing dark clothing with a hood over his head. He was last seen walking eastbound along the bridge.
Anyone with information is asked to call police at 905-453-2121, ext. 2233 or Crime Stoppers at 1-800-222-8477.