The fourth person was hospitalised with what appeared to be life-threatening injuries after the shootings, reported shortly before 4:30 pm yesterday, police spokesman Dwight Mitchell said.
Mitchell said officers believed everyone involved was accounted for but wouldn't say whether the shooter was among those shot.
"We believe there's not anyone on the loose," he said. Mitchell said the shootings took place inside an apartment but declined to say whether there were other people inside at the time at the building on the outskirts of the Highlands neighbourhood. He did not release the ages of the victims and said the investigation was just beginning.
Molly Hoekstra said she has lived in the condo complex for nearly two years but returned home yesterday to find the building blocked off by police tape.
"Nothing like this has ever happened," she said. "It's always been really safe and neighbourly. It's like the most quiet place there is.