Sheriff's deputies cleared Granite Bay High School without incident after a threatening note prompted a lockdown of the campus Tuesday afternoon.
The handwritten note, which contained a threat to shoot up the school, was found in a student restroom, according to a Roseville Joint Union High School District news release.
Lt. Andrew Scott, Placer County sheriff's spokesman, said patrol deputies responded to the campus to investigate.
Deputies conducted a room-by-room search and students were released as the rooms were cleared, the news release said. Due to the nature of search and controlled release, the end of the school day was delayed for some students.
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The Sheriff's Office, in a Twitter post, said it will continue to work with school officials to identify the source of the threatening note.
A similar threat was found by a student Friday in a restroom stall at Adelante High School in Roseville. That message contained a plan to shoot up the school that day and warned students and staff members to evacuate, according to a letter to parents.
Adelante High school administrators called Roseville police, who locked down the school and searched the campus. That lockdown lasted just over an hour.