Fire Marshal: Apartment Fire Was 'Intentionally Set'

WALTHAM (CBS) -- The State Fire Marshal said Thursday that the 10 alarm, July 23 Waltham fire that destroyed five buildings was "intentionally set."

Peter Ostroskey said this is been a detailed investigation.

"The investigation commenced early on that Sunday morning and progressed throughout the time. Six days of on site of investigative work, and then the continuous time right up until right now," Ostroskey said.

He says they concluded their investigation with the best explanation, "In this case, the investigators have determined that the fire was intentionally set."

He also said there is a $100,000 reward for information that leads to the arrest of the persons who started the fire. Ostroskey says officials are grateful for the videos and photos that have been sent in by residents.

Waltham Police Chief Keith MacPherson says fires of this size are serious, but when it's arson, "But certainly a fire of this size--an arson fire--generates a lot more concern."

Waltham Fire Chief Paul Ciccone says they're determined to find the person responsible.

"One of the early injuries we had was just from someone when one of our firetrucks was pulling up to the scene and he said he was burned by the radiant heat," Ciccone said.

WBZ NewsRadio 1030's Lana Jones reports

The Elm Street complex was still under construction so no one was living in the buildings. Fire officials also say that the solid wood construction is the reason for the rapid spreading of the fire.

Even though that complex wasn't occupied, 150 elderly residents of a nearby building had to be evacuated because of the smoke and the ash caused by the fire.

Crews from over a dozen communities were involved in fighting the fire that took over 24 hours to extinguish.

WBZ NewsRadio 1030's Lana Jones reports