A bomb threat referencing Montclair High School and its cross town rival Bloomifeld prompted the evacuation of Montclair students and faculty around 2 p.m. Tuesday, according to a school official. 

The threat had been issued in a Twitter message that day, and authorities were immediately notified, according to Montclair District Superintendent Penny MacCormack's office.

And according to Montclair High School Principal James Earle, the tweet came out of the rivalry between Bloomfield and Montclair, reported Baristanet.   

"The evacuation was ordered by the Montclair Police Department and school officials after a threat against the school was discovered in a twitter message," read a statement from the superintendent. "An active investigation is in progress."

A spokesperson from the Montclair Police Department confirmed there was a bomb threat at the school, but was unable to comment on whether the threat was credible.

Students were seen filing out of the high school after 2 p.m. The intersections around the high school were blocked off by local police vehicles. In addition, Essex County Sheriff SUVs were parked in front of the school — including the Bomb Disposal and K-9 units — and multiple Montclair Fire Department fire engines surrounded the school.

A helicopter could also be heard overhead. 

As the school day officially came to a close, students gathered on sidewalks and corners talking about the police activity. Residents in the area also stood outside and watched.

The high school was reopened as of 3:45 p.m. A spokeswoman in the superintendent's office said that students may return to the school, and all after school activities, clubs and sports will continue as scheduled. 

The following was sent to parents in an email during the evacuation: 

"Montclair High School reported a bomb threat posted on twitter to law enforcement at approximately 2:15 pm. We were asked to evacuate the building. All staff and students exited the building to safe areas and then dismissed shortly thereafter. We are operating our schools with strict safety and emergency management protocols in place. I want to assure you that student safety is our highest priority."