SUNNYVALE -- A phony bomb threat forced Fremont High School students, teachers and administrators to remain in their classrooms Thursday afternoon while officers searched the campus with bomb-sniffing dogs, the Sunnyvale Department of Public Safety said.

"It turned out to be not a credible bomb threat," said Sunnyvale Department of Public Safety Capt. Dave Verbrugge.

School officials ordered staff and students to remain on campus at 1:35 p.m., said Graham Clark, associate superintendent of the Fremont Union High School District.

Clark said all the students were safe and accounted for and that instruction continued. A phone alert was sent out to parents.

Verbrugge said the bomb threat was called in to the city dispatch center. The city sent 20 public safety officers and two dogs, and they were assisted by officers from the San Jose police department and Santa Clara County sheriff's office.

Though the threat proved to be a hoax, Verbrugge said: "Better safe than sorry."