Ottawa Police seized about 850 guns from a home in the Heron Gate area this summer.
Officers found the firearms during a call for service at the home in August. The guns were registered and most of them were legally stored, police said.
Since they were seized, the guns have been tested to determine whether any of them were used in the commission of a crime.
“Right now we have no suspicion that any of them have been used for illegal activity,” Ottawa Police Const. Chuck Benoit said.
He said the guns are being returned to the owners after being tested.
Ottawa Police Chief Peter Sloly tweeted Wednesday that the firearm seizure was due to "a tragic incident involving mental health."