The lockdown has been lifted at Scarborough's Cedarbrae Collegiate Institute.
Toronto Police say shots were fired outside the school on Wednesday afternoon.
Bullet casings were found in the parking lot, along with holes in a car that was parked there.
Other schools in the area were placed in hold-and-secure protocols.
Nobody was hurt.
Police are searching for a suspect describes a young black male with a slim build, who was wearing a black toque and a red sweater.