THOMASTON – Five tracking dogs and two cats were killed Thursday evening in a fire believed to be caused by an “intentional human element,” according to a state fire marshal investigator on Friday.

The 7:12 p.m. blaze, which caused “heavy, significant fire damage to the interior” of the home, was a “set fire” and a “suspect has been identified,” according to Investigator Tim York of the state Fire Marshal’s Office. The residence was owned by Douglas and Brigit Robinson.

Douglas Robinson is a reserve officer with the Thomaston Police Department known in town for his abilities in using his dogs to conduct searches.

Two Great Danes, three bloodhounds and two cats perished in the Sawyer Street fire, York confirmed. He said the investigation is continuing.

The person believed to have started the fire is an adult, York said, declining to say whether the suspect is a man or a woman. He said he expects charges to be brought next week.

Brigit Robinson, age unavailable, was the only person home at the time of the fire, York said. The woman was taken to Penobscot Bay Medical Center in Rockport to be examined. The investigator said he didn’t believe she was seriously injured. A hospital spokeswoman on Friday could not provide information about Robinson’s condition.

Noting the investigation was in its early stages, York said he didn’t know whether Brigit Robinson was asleep when the fire broke out.

The house is damaged to the point that it cannot be occupied, York said. He did not know if the home was insured.

“It’s a significant loss,” York said.

According to Town Clerk Joan Linscott, the property is assessed at $91,000, with the house valued at $72,120 and the land at $18,880.

Fire Chief William Adams could not be reached Friday to determine how many firefighters and equipment were called out for the fire or whether mutual aid was required.