At around 6:10 p.m., police said, police responded to an attack on a bus at the time on Sheppard East Avenue and Markham Road.
Police said the suspect and the victim were traveling east before the suspect got out of the bus through the back doors and sprayed the victim with an “unknown irritant”.
The substance caused a burning sensation, similar to pepper spray, police said.
The suspect fled the area on foot and the victim was treated by doctors at the scene.
The suspect is described by police as a woman between 20 and 30 years old, with brown curly hair up to her shoulders.
Anyone with information about the investigation is kindly requested to contact the police at 416-808-4200 or Crime Stoppers.