WALDWICK - The school district and local police are investigating a threat scrawled on the wall of a bathroom Thursday morning that prompted a lockdown of the high school and middle school.

The threat was found inside a bathroom at the high school about 10 a.m., according to Paul D. Casarico, superintendent of schools.

Following protocol, school officials immediately called police.

"All students are safe," officials said in Nixle alerts.

"After doing a thorough search of the building, the Waldwick Police, with assistance from the (Bergen) County Police and other local police departments, determined that the threat was not credible and there was no danger to students and staff," Casarico said in a statement posted to the district website.

Classes at the high school and middle school continued as usual, and police remained on campus for the rest of the day.

"Administrators will be investigating this incident thoroughly," the superintendent said in the statement. "If your child has any information that can assist in the investigation, please contact us immediately."

Officials were not releasing the contents of the note.

Classes are to resume tomorrow as normal, Casarico said.

Anthony G. Attrino may be reached at tattrino@njadvancemedia.com. Follow him on Twitter @TonyAttrino. Find NJ.com on Facebook.