SANFORD – Investigators from the State Fire Marshal’s Office were seeking the cause of a three-alarm fire that gutted a large industrial building near the Sanford Regional Airport.

More than 50 firefighters from Sanford and surrounding communities battled the Saturday afternoon blaze, which could be seen for miles. No one was working in the building at the time and there were no reports of injury.

The 120-foot-by-130-foot building housed four tenants, including a computer parts manufacturer, an electronics company, a machinery sales business and a heating and air-conditioning business.

Fire officials said the flames may have been fed by gasoline and flammable materials used by businesses in the building. Combustible materials exploded inside as firefighters fought the blaze.

Fire investigators were kept from entering the building after part of the roof collapsed. “It’s just not safe for our guys to go in it now,” Sanford fire Capt. Brian Smith said.

Two nearby buildings were not affected by the fire, and officials said they were not worried that the flames could spread to other parts of the airport.

Assistant Fire Chief Jeff Rowe said the closest fuel tank was at least 1,000 feet from the fire.

The Sanford airport is the place where President Bush arrives in Maine on his visits to his parents’ summer home in Kennebunkport. The building’s offices have been used as a staging area for the Secret Service before the president’s arrival, Rowe said.