MIDDLETOWN, Del. — Delaware State Police are investigating a bomb threat that prompted the evacuation of a high school.

State police said in a statement that the Middletown Police Department received a phone call Tuesday morning from a person who said there was a bomb at a nearby high school. The caller said the bomb would detonate if not located.

The statement says students and staff were evacuated from the school as troopers and K9 units conducted a search. Nothing suspicious was found, and students were allowed to return around 10:20 a.m. to resume normal activities.

An investigation into the incident is ongoing.