Michael Irwin, and his partner Douglas Sinclair, were attending to a call at an apartment around the corner from the overpass in February, 1972.
They weren’t aware the shooter, who lived on the fourth floor, had a history of violence, a criminal record, and was to be evicted.
Diplomacy failed after the man answered the door gripping a rifle.
“They went out of their way to make our community safe, and that’s important for all of us to remember,” said Insp. Sam Fox who was on duty when the tragic incident occurred.
Several of Irwin and Sinclair's sons and nephews have since gone into policing, including Ian MacGregor who accepts that it can be a difficult and dangerous profession.
"I come into police work with my eyes open," said MacGregor, who is one of Sinclair's nephews. "There are incidents that can take your life. It's something that actually happened in our family."
The CBC's Amanda Margison reports.