The incident happened near Victoria Park and Surrey avenues around 3:30 p.m
According to police, a passenger was trapped in a vehicle and was found unconscious. Emergency crews performed CPR through the car window and were able to revive them.
An elderly woman was taken to a trauma center in serious condition, police said.
Paramedics say two other patients, a man and a woman, were taken to hospital with non-life threatening injuries.
Roads in the area are closed while police investigate the incident.