SAN BRUNO, Calif. (KTVU) - Hazmat crews responded to a San Bruno elementary school after a kindergarten teacher received a letter containing an unknown substance that was later deemed not harmful.
According to the San Bruno School District, San Bruno police were contacted after the Portola Elementary School kindergarten teacher received the letter around 10:40 a.m. Wednesday.
"A staff member at the school had opened a letter. It was a threatening letter and contained a suspicious substance," said San Bruno Police Lt. Ryan Johansen in an online video statement.
Teachers responded quickly and students were kept in a secure location away from the substance and the school was placed on lockdown.
San Bruno police, Hazmat and fire crews responded and determined the substance was not harmful.
"At no time did any students or staff show nay symptoms of a poisonous substance," said San Bruno Fire Chief Bill Forester.
Police are investigating the incident.