Toronto police responded to a collision in the area of ​​Kingston and Galloway streets around 9:30 a.m.
A pedestrian woman in her 40s or 50s was hit by a vehicle and found unconscious, police said.
Toronto rescuers said he was taken to a trauma center in serious condition.
The driver involved remained at the scene, according to police.
The cause of the collision is unknown.
The area is closed as police investigate and TTC vehicles have changed course.