The five-alarm fire that ripped through a Windham warehouse earlier this week, destroying a business and a handful of high-end boats, has been ruled accidental, investigators with the State Fire Marshal’s Office said Wednesday.

The blaze likely started in one end of the L-shaped building, a section that was used as storage by Royal Flush Septic, said Windham Fire Chief Charlie Hammond.

No one was hurt in the fire. Firefighters from nine surrounding communities helped the Windham Fire Department battle the blaze, Hammond said.

The fire set off a burglar alarm in the building Monday at around 2:45 a.m., sending a signal to Windham police, who responded to the alarm at 35 Cherry Lane, near the intersection of Gambo and River roads.

“The police department arrived there looking for a burglar and found a fire,” Hammond said. “There was fire through the roof at that point.”

Firefighters responding to the call said they could see smoke billowing from the fire from the rotary on Route 302 in Windham, and the bright glow of the fire was visible from Route 202.

By 10 a.m. nothing but burnt rubble remained over the section of the building taken by the fire. Less than a third of the 15,000-square-foot warehouse remained standing, and another nearby building was damaged. The barely recognizable remains of boat trailers and motors, melted by the fire, could be seen in the wreckage, covered by black soot and burned wires.

“It was a big fire. It’s been a while since I’ve seen that volume of fire in a building,” said Windham Fire Chief Charlie Hammond. “Once that metal gets burning, it burns hot. And you’ve got the fiberglass in the boats, which also burns hot.”

In all, six boats were destroyed and another two were damaged, said Sean McGoldrick, owner of the buildings, which are used for winter boat storage. Three of the water crafts were cigarette boats with twin blower engines, and a fourth was a Sonic racing boat with three blower engines, he said.

“They were worth a lot,” said McGoldrick. “I couldn’t even put a figure on it.”

The boat owners have been contacted, McGoldrick said.

“They’re devastated, but they’ve been real reasonable with us,” he said.

In the section of the building used by Royal Flush, the burned out chassis of an older model car could be seen among the debris. Eddie Dunn of Windham, an employee at Royal Flush, said the company’s owner had been storing the 1987 Monte Carlo at the site while it was being restored. The car was in perfect condition, Dunn said.

McGoldrick is not sure what he and the other owners will do with the building.

“Right now we are letting the smoke settle,” he said. “We haven’t made any decisions yet.”

Dramatic Windham fire ruled accidental