Perry Hall High School was placed on alert status after a school system employee made a verbal threat against the school.
The employee was not on campus when he made the threat. In response, the school was placed on alert status, meaning Perry Hall continued normal activity indoors, but did not allow activities outside the building.
Although the threat was made after school dismissal, some students were still on the school campus when it happened.
Baltimore County Public Schools said two officers were stationed on school property. Police said the suspect was arrested.