Ontario Provincial Police, acting on a tip, raided the Bancroft, Ontario, home of David Alan Kift, 55, last week, the Canadian Broadcasting Corp. reported.
Investigators said they found handguns, assault rifles, machine guns, a fully automated shotgun, crossbows and a stun gun. They also discovered grenades, landmines and detonator cords.
Police said the weapons cache was found in two hidden compartments built into the walls of the house.
"What this investigation tells us is that copious amounts of firearms and ammunition were collected, stored and sometimes even created well away from big-city Ontario," Detective Inspector Patti Dobbin told reporters Tuesday.
Police said some of the assault rifles were homemade and guns had no serial numbers.
"The assault rifles, the ARs, they have no markings on them at all," said Durham Regional Police Detective Jamie Derusha. "And that causes us a lot of concern."
Kift is jailed on multiple counts of weapons-related offenses, including illegal possession, manufacturing prohibited and restricted firearms, and illegal possession of ammunition and explosives, and breach of parole conditions, the CBC said.
Kift left the Royal Canadian Mounted Police in 1996, Inspector Mario Lessard of the Durham Regional Police said. He was on parole with a lifetime ban on possessing firearms.
Marion Kift, 53, also of Bancroft, faces multiple counts of similar charges, police said. She was freed after a bond hearing Monday, the CBC said.
"This is a significant discovery and we are pleased that these weapons are now secure," Lessard said.
"As police officers, we never want to see this kind of firepower in one place. It tends to attract attention and could be the target of criminals who want these weapons for their illegal activities.