An apartment patio fire in southwest Bend Saturday night was put out and stopped from spreading inside by a single activated fire sprinkler, officials said.

Bend Fire & Rescue responded around 10:15 p.m. to the reported fire on a first-floor patio at the Stillwater Crossing apartment complex on SW Atwood Drive (near Highway 97 and Ponderosa Street), Battalion Chief Scott Wyman said.

Two fire engines, a medic unit, a ladder truck and a command vehicle went to the scene, where residents of the apartment building had evacuated.

The first engine crew to arrive found a smoldering fire that already had been extinguished by the fire sprinkler, Wyman said.

Firefighters confirmed the fire was fully out and shut down the sprinkler system. Wyman said all residents were able to return to their apartments.

Deputy Fire Marshal Cindy Kettering said, “This was an exterior fire that was held in place, held in check by an exterior sprinkler.”

“Commonly, when we see fires that start on an exterior side of a building, they can go up the siding into the eaves and spread into the attic space and turn into a very large and challenging fire,” Kettering said.

But in this case, she said, “There were fire sprinklers in this building. That single one sprinkler head activated and basically extinguished the fire before we even arrived on scene.”

An investigation determined the fire’s likely cause was improper disposal of cigarette smoking material, Wyman said.

Damage was limited to $2,000 worth of contents and minor damage to the structure.

“The sprinkler system prevented significant loss to the structure and displacement of multiple occupants,” the battalion chief said in a news release.

“National data show that the presence of fire sprinklers in residences drastically reduces the fire damage and potential for loss of life,” Wyman added.