Threatening graffiti found at Livermore middle school

LIVERMORE, Calif. (KTVU) - Security was heightened at a Livermore middle school Tuesday after threatening graffiti was found on campus. 

School officials at Mendenhall Middle School found the threatening graffiti early in the morning on a wall at the back of the school. 

Livermore police were immediately called and will remain on campus for the rest of the day and throughout the week. 

The school hasn't received any additional threats and officers haven't determined the credibility of Tuesday's threat, but there will be additional patrols at all school sites in Livermore throughout the day.