MEXICO – Following an investigation on Wednesday, a state fire investigator labeled Tuesday afternoon’s fire that heavily damaged a third-story roof at 140 Granite St. in Mexico as arson.

There were no injuries.

Office of the State Fire Marshal investigator Chris Stanford said early Wednesday evening that three 13- and 14-year-olds from the Mexico-Rumford area started the fire in a combination “knee wall” or half wall, and roof rafter on the third floor.

“It was definitely an incendiary fire that was intentionally set,” Stanford said. “It was very dangerous, because it’s an older building in the process of being demolished, with wide open holes in the floors and walls, so it had all the oxygen it needed to take off. Another five minutes and it probably would have been totally involved.”

He credited a fast response and attack by Mexico and Rumford firefighters with preventing the fire from spreading.

Enforcement actions and prosecution of the children on felony arson charges are up to the district attorney’s office.

“The DA could decline to prosecute depending on circumstances, or prosecute them to the full charge of arson. It would still be Class A, but with juvenile crime, you don’t go through a grand jury. The focus of the juvenile justice system is to rehabilitate rather than punish,” Stanford said.

The teenagers gained access to the third floor through the livable section, but prior to doing that, he said they used ground ladders.

Stanford declined to identify the incendiary device, but did say that an open flame was used to start the fire.