by Martin Weil

Graffiti at a Northern Virginia high school indicated that a student planned to bring a weapon to school Tuesday, authorities said.

A recorded call regarding the incident was made Monday evening to parents of students at Potomac High School in Prince William County.

Authorities said they had no evidence that the graffiti embodied a credible threat. However, officials said police were expected to bolster patrols at the school Tuesday.

They said the message was apparently found on a stall in a bathroom, and was being investigated.