BENTON — State fire investigators continue to probe a fire that destroyed a vacant house on Unity Road that officials say is suspicious.

“I would say it was definitely something that we’re interested in finding the cause, because there was no power and nobody lives there,” Travis Leary, chief of the Fairfield and Benton Fire-Rescue Department, said Friday.

Leary and about 20 firefighters from several towns responded to the fire at 864 Unity Road at 3:50 p.m. and remained there until about 9 p.m. Thursday. Firefighters returned a little after midnight to put out a small fire between the roof layers and the top of a wall, Leary said. They spent about an hour doing overhaul work, he said.

Leary, who called the Office of the State Fire Marshal Thursday to help determine a cause, said he spoke with a state fire investigator Friday morning who said they got called to a fire in York, so the Benton fire is still being investigated.

“It’s still ongoing,” Leary said. “They had to get in touch with the owners … they’re basically following up on all that.”

Leary said the owner of the unoccupied house died several years ago and the property is in an estate. The son of the former owner lives out of state, he said. Leary described the house as a “total loss” and said he is not sure if it was insured.

Leary said he spoke to the son of the former owner of the property and was told the house had been vacant for at least six years. The wooden house with additions built onto it was accessible by a dirt driveway off Unity Road that dipped down to a wooded area and was flanked by tall grass and bushes.

At the scene Thursday, Aaron Owens, 44, of Waterville, stood watching emergency crews at work. He said a man who used to live at the house was a race car driver who raced at the Unity Raceway. Owens said he would always pass by the house on his way to Unity during those years to watch the races.

“I hadn’t been to the races in years and just recently started again,” he said. “I saw that the house was vacant. Now, this happened. It’s unreal.”

Owens said that when he was growing up, his father and stepfather were both firefighters and he listened to a police scanner. He still does, and often drives to fire and accident scenes, he said.

Firefighters from the Fairfield-Benton, Albion, Unity and Winslow fire departments worked at the scene Thursday, and Waterville firefighters covered the fire station in Fairfield. The Kennebec County Sheriff’s Office, Clinton Police Department and Delta Ambulance were also at the scene.

A Fairfield firefighter was treated for heat exhaustion at the scene but was not taken to a hospital, Leary said.