Parents in Dumfries, Va., warned of threatening graffiti

A Prince William County high school is on alert after a student may have been planning to bring a weapon to class Tuesday.

Parents at Potomac High School in Dumfries, Va., received a recorded call Monday night. It said that graffiti indicating the threat had been found on a bathroom stall.

Prince William County Police say additional officers will be on patrol in the area tomorrow, but school officials and detectives say there's no evidence that the graffiti is a credible threat.