Law enforcement have increased their presence at Del Norte High School on Thursday and Friday after graffiti mentioning a bomb and shooting was found in a boy's bathroom on Wednesday.

The threat isn't considered credible, Crescent City Police Chief Ivan Minsal said, but his department is working with school officials to determine who the source of the graffiti is. A janitor servicing one of the boy's bathrooms discovered the graffiti Wednesday evening, Minsal said.

"It was determined to be more of a prank as opposed to an actual threat," he said, adding that law enforcement hasn't found any devices or anyone with a gun and hasn't received any reports of injuries. "But we take these all seriously and we are still investigating to determine who put this out there."

The Crescent City Police Department is currently conducting a criminal investigation, Minsal said. High school principal Randy Fugate has also worked with the school resource officer reviewing surveillance footage, he said. There is no threat to the school or its students at this time, Minsal said.

Meanwhile Crescent City Police officers have also increased their presence on campus. Minsal said he has also asked the Del Norte County Sheriff's Office and California Highway Patrol to visit the high school if they had a few extra minutes "so everybody's fears can be laid to rest."