Classes in the six-school Monroe Township Public Schools were canceled with police present at Williamstown High School.
In an announcement to the school district, Superintendent of Schools Susan B. Ficke said the principal at Williamstown High School received an email of a threat of school violence which was to occur Friday.
"We received the threat prior to the scheduled school day. There were approximately 30-50 students already at the school at the time," the superintendent wrote. "The threat named specific individuals and the school was immediately placed on lockdown."
Ficke did not specify whether the threat was made against certain students or school staff members.
Incoming buses were redirected from the school.
Numerous police officers from several jurisdictions throughout Gloucester County cleared the schools and buses, she said.
The Monroe Township Office Department, along with the Gloucester County Prosecutor's Office and the FBI are actively investigating this threat.
"We are also working closely with the Monroe Township Police Department to ensure that our students and staff are safe. If anyone has any information, please contact the Monroe Township Police Department," the superintendent wrote.
Click here to follow Daily Voice Edison and receive free news updates.