About 640 Julien Elementary School students in Turlock were evacuated Friday morning after a school librarian found a suspicious bag and office staff received a threatening phone call, police said.
Office staff picked up the phone and the voice on the other end said "Boom" and hung up, police said.
The Stanislaus County Sheriff's Department bomb squad X-rayed the bag about 11:30 a.m. and found it was full of trash. They walked through the school twice before letting students back on the East Canal Drive campus.
Police evacuated the school and some neighboring Turlock High School summer school students about 9:11 a.m.