Bainbridge High School was put on lockdown just before noon Wednesday after 911 dispatchers received an anonymous phone call that said someone had entered the school’s cafeteria with a gun.

Bainbridge Island police officers — along with multiple units from the Kitsap County Sheriff’s Office and the Poulsbo Police Department — raced to the school on High School Road. Officers in tactical gear, some armed with assault rifles, swept the campus.

School officials warned students over the school’s intercom that it was not a drill, and police gave the all-clear after about 30 minutes of searching. No gun was found.

Roughly a dozen parents gathered across from the high school near the Grove Avenue intersection, trying to reach their children via cell phone, during the lockdown.