Police investigate possible threat at San Mateo High

Classes have resumed as normal at San Mateo High School after the campus was placed on lockdown due to an unspecified threat Wednesday afternoon.

Police were investigating a possible threat written on the wall of a bathroom at the school.

According to authorities the school was  placed on a "secured campus" alert to "err on the side of caution."

San Mateo Police say the San Mateo County Sheriff's bob squad was called out and determined there was no credible threat.