Some 50 to 75 people living nearby vacated their homes after what looked like artillery shells and large calibre bullets were discovered in a vacated apartment unit on Louvre Street.
Police had set up a perimeter in the surrounding neighbourhood but later narrowed it to the apartment itself.
On Thursday, Gatineau police sources told Radio-Canada the former tenant's son had come forward and is co-operating with investigators.
Police said criminal charges are unlikely.
A team from the Canadian Army came to check the devices and deemed them not a threat, Gatineau police said.
Police said Thursday they and the Army continue to investigate the legality of having these weapons in a home.