Jamy Pombo Sesselman

Senior Digital Editor/Producer, WCVB.com

BILLERICA, Mass. —

Police responded early Thursday to a bomb threat at Billerica Memorial High School in Billerica, Massachusetts.

Police said the threat was called into the school at 6:15 a.m. The threat was made before any students had entered the building.

As students arrived at the school, they were brought to a field on school property under the supervision of staff, police said

A NEMLEC K-9 Unit assisted police with sweeping the school building to ensure the building was safe for students to enter.

“The Billerica Police Department is investigating the source of the threat and will update the public as pertinent information becomes available,” police said.

Students have returned to class.