WBZ-TV

Firefighters investigating what has been described as the biggest blaze in Boston in decades say the fire was caused by some men setting off fireworks from a the roof of a nearby building.

Fire Lt. Hank Sheridan said on Tuesday that the men caused the fireworks to travel to the stricken warehouse, igniting the roof and triggering a nine-alarm blaze that brought in about 170 firefighters from across the city.

The fire was reported on Saturday night in the city’s Roxbury neighborhood and was not completely out until Sunday afternoon. No one was hurt. It caused an estimated $750,000 in damage.

The cause was determined after investigators examined physical evidence, interviewed witnesses and reviewed burn patterns together with other factors.

The culprits may be cited for illegal activity. The fire has been ruled accidental.