Four people have been shot in multiple incidents in Rexdale and Etobicoke on Friday evening in what police called "a running gun battle."

At around 6:35 p.m. ET, police responded to a call in the Mount Olive Drive and Kipling Avenue area of Rexdale following reports of gun shots fired into the street-level common area of an apartment complex that injured three people.

According Supt. Ron Taverner of Toronto Police Service 23 Division, there were multiple shell casings scattered throughout the area when police arrived.

Toronto EMS confirmed that two people, one 23-year-old male and one 24-year-old female, were transported to hospital from the complex at 1 Mount Olive Drive. The male victim had gunshot wounds in the right hip and was taken to a trauma centre in serious condition. The female received a gunshot wound in the ankle, and was taken to a local hospital in stable condition.

A third person injured at the scene was transported by members of the public to Etobicoke General Hospital after being shot in the right buttocks. Police believe that the shooter followed the vehicle and attempted to shoot the victim again when they exited the car outside of the hospital.

During that incident, a fourth person was shot. The victim was taken to the trauma centre at Sunnybrook Hospital with life threatening injuries, police said.

Extra police were called to Sunnybrook after staff became concerned that more violence could ensue when the victim arrived, and the hospital is currently under lock down.

Three of the victims have been discharged from hospital, while one of the four remains at Sunnybrook in critical condition.

Heavily armed police officers could be seen searching the area around the apartment complex on Mount Olive Drive and talking to potential witnesses well into the night.

Investigators were also probing a scene on Martin Grove Road that police said may be linked to the shooting.