An investigation into two fires at the Pentucket Regional Middle and High School easily found the cause of one but left the other as undetermined.

The building, which is under construction, will be a three-story facility for both middle and high school-aged children.

A fire on the roof that sent black smoke into the air on Friday, August 5 was brought under control within a half-hour of the arrival of fire crews, according to West Newbury Fire Chief Michael Dwyer.  An investigation determined the fire was caused by sparks from a grinder that ignited a nearby adhesive.

Two days later, flames broke out again at the building on Main Street around 3:45 p.m., again bringing mutual aid when the fire went to two alarms.  The second fire was also quickly extinguished.

Response to a second fire at the site of the Pentucket Regional Middle and High School building project. (Mass Fire Buff)

A joint investigation by the West Newbury Fire Department and the State Police Fire & Explosion Investigation Unit identified several possible causes including electrical wiring and smoking materials. Because all but one possible cause could not be eliminated, the cause of the fire will officially be undetermined.

Dwyer said there is no evidence that the fire was intentionally set.

Contact reporter Dan Alexander at or via Twitter @DanAlexanderNH

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