A video showed Roberta Road Middle School in Concord as students and parents left the building during an open house.
Parent Johnny Jackson said everyone was moved to the gym and auditorium for about 30 minutes.
“We heard thunder,” Jackson said. “Lights went off for a while. They were restored quickly – (a) bunch of yelling – (a) bunch of kids yelling.”
Harrisburg Fire Battalion Chief Jason Walker said he and his family were at Mount Pleasant Middle School. He said everyone remained calm and he praised the faculty and staff for how they handled it.
Each middle school will communicate with parents about how to pick up their kids’ schedules. High school open houses will now be on Tuesday.