TUCSON, Ariz. - Marana police investigated a threatening graffiti message left in a boy's restroom at Marana High School.
According to Marana Unified School District, police found the threat -- which referenced a school shooting -- to be not credible.
As a precaution, Marana police will remain at the high school Friday. Classes are proceeding as normal.
Parents and students were asked to share any information they have about the message.