VALLEJO -- Spray-painted graffiti referring to the Islamic State closed a Bay Area elementary school Thursday, CBS San Francisco reports.
A custodian found the graffiti on the rear wall of a classroom building on the east side of Elmer Cave Language Academy at 7:20 a.m., Lt. Herman Robinson said.
The station reported that the graffiti said "ISIS" and threatened to blow people up, but that it also included drawings of male and female body parts and local gang symbols, leading investigators to believe the crime was committed by juveniles.
There are no surveillance cameras in the area where the wall was spray-painted, Robinson said.
The Vallejo City Unified School District posted an emergency parent notification on its website Thursday morning about the threat and the decision to close the school. The message referred to a "potential terrorist threat." But police said they believe there is no credible terrorism threat related to the graffiti, according to the station.
In light of recent mass fatal shootings, Robinson said the graffiti at the Vallejo school "raised some red flags" and that the school was closed today out of an abundance of caution.
Students were given the option today of attending Vallejo Charter School instead of their own school.