C. Milton Wright High School in Bel Air was evacuated Thursday morning for a bomb threat that turned out to be unfounded, Harford County Public Schools officials reported.
The threat was delivered in the form of a note.
"The written note was found at approximately 10:30 a.m. this morning," spokeswoman Teri Kranefeld said Thursday afternoon, calling the threat "unspecified."
"Law enforcement was immediately notified and the students were safely evacuated," she said. "The police conducted a thorough investigation of the building and deemed it safe for the students to re-enter."
Harford County Sheriff's deputies responded to the school. Entrances from Route 543 were blocked by police cruisers while the school was evacuated and checked.
Eddie Hopkins, chief of the Bel Air Volunteer Fire Company, also responded, explaining his response was "routine." He said the fire company had a crew standing by at the station as a precautionary measure.
The students were evacuated to the football field at rear of the school, a deputy at the scene said.
The students were allowed back in the school shortly after 11:30 a.m., Kranefeld said.
Aegis staff member Matt Button contributed to this story.