Residents of an apartment complex in suburban Toronto say they heard multiple gunshots and are fearing for the safety after a "running gun battle" that carried on outside the emergency room of a hospital, and ended up injuring four people.

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

Police said four people were shot in multiple incidents in the Rexdale neighbourhood and Etobicoke in what they have called "a running gun battle."

CBC News on Saturday spoke to residents who didn't want their names used, but described what they saw and heard.

Toronto police believe there may be up to four suspects involved in the shootings Friday night in Rexdale and Etobicoke. (Marley Parker/CBC) "Pop, pop, pop, like many times,” one woman said about the gunshots, adding that kids were playing outside at the time.

Police say at least 20 rounds were fired.

"I started running," another woman said.

One neighbour who feared retaliation, so didn’t want to be identified, described seeing a woman and one-year-old child caught in the gun battle. “I thought she was dead because she was right in the midst of the popping."

Police said Saturday that one of the people who were shot was driven by a friend to Etobicoke General Hospital, unaware they were being followed, and shots were later fired outside the emergency department, resulting in two more injuries. Two people were then rushed to Sunnybrook Hospital, where a lockdown was issued as a precaution

On Friday night, after the incidents, Toronto Police Services' emergency task force spent hours in search of clues.

Supt. Ron Taverner of 23 Division said multiple shell casings were scattered throughout the area when police arrived.

Toronto EMS confirmed Friday night 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 man had gunshot wounds in the right hip and was taken to a trauma centre in serious condition. The woman received a gunshot wound in the ankle, and was taken to a local hospital in stable condition.

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

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

Police said they believe there were four suspects, two vehicles and multiple firearms involved in the melee, and up to 20 shots were fired.