DETROIT (WWJ) - Students and staff were evacuated from Henry Ford High School Friday morning after an apparent bomb threat.

While it wasn’t immediately clear when the threat was made, the school was evacuated just as the day was beginning around 8 a.m.

Tyrone Winfrey, EAA Chief of Staff, said three separate police K-9 units searched the school are surrounding area, but found nothing.

Winfrey said students and staff were allowed back inside of the school around 9:20 a.m. after a security sweep was successfully completed.

The school, which is part of the state’s Education Achievement Authority, is located on Evergreen Road just south of 8 Mile Road on the city’s northwest side.

It wasn’t immediately clear who made the threat or what the threat contained.

An investigation is ongoing.