CHICORA — State police say they expect to file arson and other charges against a 31-year-old woman suspected of setting a house on fire Wednesday night.

The fire at the home on Water Street was first believed to be accidental but a more in-depth investigation Thursday by a state police deputy fire marshal determined it was intentionally set, authorities said.

No one was home and there were no injuries. The fire caused a little more than $10,000 in damage to the house and its contents.

Jason Ramsey and his girlfriend’s 23-year-old daughter live at the single-story, two-bedroom home. The two roommates had left between 3 and 4 p.m. Wednesday.

Ramsey, who rents the house, said he got a call from a friend about 9:15 p.m. informing him of the fire.

A passing motorist saw smoke and flames coming from the home and notified authorities. The first fire crew was there in two minutes, said Rick Craig, an assistant chief with the Chicora Volunteer Fire Department.

“We saw flames coming up from a (bedroom) window,” he said. The fire was coming from outside the window, which was fitted with an air conditioner.

“It was burning pretty decently,” Craig said

An attack crew pressed its way through the locked front door and other firefighters used a pole to dislodge the air conditioner from the window.

Almost immediately as firefighters entered the house, a pet dog ran out and was not hurt.

From inside, the crew attacked the fire with a pressurized water can. From outside, firefighters used a hose line. The combined effort, authorities said, quickly snuffed out the blaze.

Firefighters later pulled off the aluminum siding around the window to make sure any hidden hot spots were extinguished.

Chicora fire officials initially advised police that a faulty air conditioner appeared to have started the blaze.

But an investigation by Trooper David Jungling, a deputy fire marshal, determined the fire was no accident.

Police believe the suspect, who they did not identify, removed the air conditioner to get into the home. It was not known if she took anything. She apparently left through the same window.

Police Lt. Eric Hermick said police have interviewed the suspect, a former girlfriend of Ramsey, and said she would likely be charged with arson and burglary today or Saturday.

The home, owned by Harley Flick of Chicora, was not insured, authorities said. The occupants did not have renter’s insurance.

The damaged window was eventually boarded up and the electricity was turned off pending an inspection.

An official for the Butler chapter of the American Red Cross said the agency is assisting two occupants with temporary housing.

About 30 firefighters from five departments battled the blaze and remained there for nearly two hours.