SANTA MONICA, Calif.—Authorities searched the campus of Santa Monica High School Nov. 3 in response to a telephoned bomb threat that prompted a lockdown, but no devices or suspicious items were found.

“At approximately 11:42 a.m., the switchboard operator received a phoned-in bomb threat, alleging the bomb was set to go off within five minutes,” school Principal Marae Cruce said in a statement to the parents and others.

“The school contacted the police immediately following this phone call. The school is currently in a shelter-in-place, and all students are safely in classrooms.”

At about 1:30 p.m., police wrote on Twitter that officers were “conducting a thorough search to ensure the students remain safe. The K9s are on scene and continuing the search.”

About an hour later, police announced that the search had been completed, with nothing suspicious found. The campus lockdown was lifted, and students were released from the day.