MILL VALLEY (CBS SF) – Police in Mill Valley said Mill Valley Middle School was evacuated as a precaution after a bomb threat was called in Tuesday morning.

The school reported emailed parents about the threat shortly before 10 a.m. Mill Valley police issued an alert about the bomb threat at about 10:15 a.m.

Children were safely evacuated at the Mill Valley Community Center at 180 Camino Alto, where parents were told to pick them up.

“I originally thought it was a joke, because that’s what you hope it is. But then I got scared for my son because, you know, he’s inside and probably scared. Which he was,” said one Mill Valley Middle School parent.

Additionally, all residents within a half-mile of the school were advised to shelter in place until further notice.

The Mill Valley police and fire departments evacuated the school at 425 Sycamore Ave. while it is inspected.

No device was located and the “all clear” was announced shortly before 1 p.m.

The source of the call is still under investigation. Authorities ask that anyone with any information on the threat please contact Mill Valley police.