A fire burned through the attic of a beachside cottage at the historic Chatham Bars Inn early Friday morning as patrons managed to escape the flames, officials said.

Firefighters responded to an automatic fire alarm at one of the inn’s cottages at 340 Shore Road around 2:15 a.m. Friday, Chatham fire Lieutenant R.J. Sylvester said.

All four of the cottage’s rooms were occupied at the time of the fire, and all tenants were alerted by smoke alarms and evacuated themselves safely as firefighters arrived.

The Shore Road cottage is one of 30 wooden Cape-style lodgings scattered across the inn’s historic property. The Chatham Bars Inn, recognized as one of Cape Cod’s top resorts, was built in 1914 across around two dozen acres along eastern Chatham shores where the cottage burned.

After the fire alarm was triggered Friday morning, firefighters arrived at the cottage around 2:20 a.m. Smoke was issuing from the upper portion of the building, and a working fire assignment was issued, Sylvester said.

“The captain reported white smoke reporting from the entire length of the eaves on side A, which is about 80 feet across,’’ he said. “It’s a fairly large building even though it’s listed as a cottage.’’

The Chatham Fire Department said on Facebook that firefighters quickly brought a hose line up to the second floor to attack the blaze, and the cottage’s roof and gable end were vented.

Sylvester estimated the fire was knocked down by around 2:35 a.m. Firefighters remained on scene until around 4:44 a.m. Fire crews from Harwich, Orleans, and Brewster assisted Chatham firefighters at the scene.

No one was injured in the fire.

Damages were estimated at around $200,000, rendering the cottage “unusable,’’ Sylvester said.

The cause of the fire is unknown, and it is under investigation.

Ben Thompson can be reached at ben.thompson@globe.com. Follow him on Twitter @Globe_Thompson.