More than 50 calls from concerned residents came into the OC Sheriff's Department early Tuesday after a siren sounded at the San Onofre Nuclear Power Plant.
The siren -- a false alarm -- sounded at about 4:45 a.m.
"We got a whole bunch of calls," said Sgt. S. Baker of the Orange County Sheriff's Department. "Not sure how many, but it was a parcel. A whole bunch."
The siren was shut off almost immediately and determined to be a false alarm, Baker said. He said authorities are not sure what triggered the alarm.
Technicians at the plant were looking into the problem, Baker said.