A bomb found in the Groveland area Monday morning caused all kinds of problems for motorists and residents in the area.
The device was found just before 10am Monday hanging off a road sign at Memorial Drive, between Big Oak Flat and Groveland.
According to the California Highway Patrol, Highway 120 was closed briefly as the Calaveras County Bomb Squad blew up the device.
Officials delayed the operation until around 5pm Monday evening because they were concerned about winds posing a wildfire risk.
They also spent time looking for possible secondary explosives in the area.
PG&E says 2370 customers experienced a brief interruption in power from Big Oak Flat to the Yosemite park boundary between 5 and 5:30pm as the operation was being executed.
And the CDF also sent a helicopter to the area as a precaution to provide a view from the air as well.
Sergeant Roger Dittburner with the Tuolumne County Sheriff´s Department says the case is under criminal investigation.