Toronto police say a teenage boy has been stabbed on a public transit bus in the city's west end.
First responders say the 16-year-old victim has been taken to a trauma centre with serious injuries following reports of a stabbing just before 4 p.m.
Police described the suspect as a person in their 20s with a medium build, wearing a blue mask and blue jacket with the hood up.
Police say officers are on scene investigating and are asking anyone with information to contact them.
The stabbing is the fourth case of violence in five days on the city's transit system.
In recent days, a woman was stabbed on a streetcar, two uniformed TTC workers were assaulted on their way to work and a TTC driver was shot with a BB gun.