A Torrance high school was put on lockdown for several hours Wednesday as police investigated a bomb threat.

Around 11:30 a.m., someone called police, said there were multiple bombs on the South High School campus and hung up, according to Torrance police.

The school was placed on lockdown as officers arrived and evacuated nearby homes and pedestrians. Nearby Richardson and Calle Mayor middle schools sheltered in place, according to the Torrance Unified School District.

As of about 3:30 p.m., police said they hadn’t found anything suspicious, but police dogs trained in explosive detection were searching the campus. By 4:30 p.m., district officials said all three campuses were determined to be safe.

All schools were cleared for dismissal, though the parking lot and some roads around South High School remained closed by police.

The public was also asked to avoid the area near Pacific Coast Highway and Calle Mayor as the investigation continues.