At about 2 p.m., the bomb team blew up the grenades inside a makeshift bunker they dug in the front yard of a home in the city's Cambrian Park neighborhood, sheriff's Deputy Kurtis Stenderup said.
The deputies had decided that the military grenades, made in China before the end of World War II, were too unstable to transport to another location, Stenderup said.
The grenades were found in a box inside a home in the 15000 block of Chelsea Drive in unincorporated San Jose by a caregiver who was cleaning the home after its owner had died recently, Stenderup said.
The caregiver made an emergency call at about 10:30 a.m. and deputies responded, along with the Santa Clara County Fire Department, Stenderup said.
Deputies evacuated residents from surrounding homes and firefighters shut the gas off to the home as a precaution, Stenderup said.
Firefighters and other emergency responders were assigned to a command post nearby, Stenderup said.
People in the neighborhood and the news media stood by and watched the controlled explosion, Stenderup said.