After more than two weeks of firefighting, the Ptarmigan Fire near Silverthorne reached 100% containment Thursday, the U.S. Forest Service announced.

The fire sparked on Sept. 27, immediately burning 86 acres but not growing since Sept. 28, fire officials said. The cause of the fire is still unknown.

Full containment was reached after weather brought several days of moisture to the area, the forest service said.

“We appreciate the close coordination among the many agencies and organizations involved in the Ptarmigan Fire response,” said Deputy Dillon District Ranger Chris Stewart. “We also appreciate the support and patience of the community.”

Firefighters will continue to patrol and monitor the burned area over the next several weeks, Stewart said.

Closures are lifted for the burn area and the trails leading to it; however, fire officials warn the public to be cautious of falling trees and rocks in and around the burn area.

The fire prompted evacuations and warnings for more than 600 residents in the Hamilton Creek, Angler Mountain Ranch, South Forty and Ptarmigan neighborhoods. Those orders were downgraded and canceled in the days following the fire’s ignition.

At its peak, nearly 300 firefighters were working to fight the blaze, according to the forest service.

The Summit County Sheriff’s Office, fire department and forest service will hold a community debrief about the fire on Oct. 21 at 6 p.m. at the Silverthorne Town Hall, 601 Center Cir.