DURHAM — Police Saturday night were investigating the cause of an early-morning garage fire at 253 Quakermeetinghouse Road, which caused about $50,000 in damage, fire Chief St. Michel said.

He declined to speculate on the cause, saying a representative of the State Fire Marshal’s Office would be at the scene on Monday.

The fire at the detached 1½-story, two-bay garage at the sprawling Thanksgiving Farm owned by Jim and Barbara Stanley was called in at 4:32 a.m. and was brought under control in about half an hour, St. Michel said.

The Stanleys said they were awakened by a crackling sound followed by an explosion; they saw an “orange glow” outside.

The owners immediately ran to the nearby barn and led four horses to safety, Jim Stanley said. The garage is located about 30 feet from the large farmstand.

When firefighters arrived, a caretaker was using a garden hose in an attempt to quell the blaze. There was heavy smoke in the upstairs portion of the wood-frame structure and the garage door windows were blown out.

No nearby structures were threatened. However, a 2008 Chevy pickup truck with an attached horse trailer parked in front of the garage sustained between $5,000 and $6,000 in damage, St. Michel said.

He estimated combined structural and smoke damage to contents stored on the second floor to be between $40,000 and $50,000.

No injuries were reported. Assisting Durham firefighters at the scene were one engine and a tanker from Lisbon Falls and one tanker from Freeport. Pownal Fire Department filled in at the Durham station.