The Fontana Police Department found a grenade at a house in the 8100 block of Banana Avenue in western Fontana on the afternoon of July 16, resulting in the evacuation of some of the nearby residents and business owners.
The grenade was rendered safe, and so the evacuation was lifted after about two hours, police said.
The incident began when police were asked to conduct a welfare check on an elderly couple, and when officers entered the residence, they found more than 100 guns as well as the suspicious device.
As a precaution, police called for the San Bernardino County Fire Department and San Bernardino County Sheriff's Bomb squad to come to the location to check the device.
Police continued to investigate why the grenade was at the location.