Danville police are investigating a school threat set for Tuesday and are beefing up patrols in the area.
A jogger found a threatening message Sunday painted on a footbridge off Old Blackhawk Road. The message has been painted over, but police said it read "Shooting at MV and SRV 10/3," an apparent reference to Danville's two high schools Monte Vista and San Ramon Valley.
Police have been investigating, but said the threat does not appear credible.
Investigators said they do not have anything to corroborate the threat, but officers will still take precautions and be out in force Tuesday to make sure students feel safe.
Authorities said there was a very similar incident a few years ago, a threatening message left on a footbridge, but it targeted a different school. Nothing happened in that incident, police said.