Dec. 15 (UPI) -- A wildfire in South Dakota's Custer State Park that ballooned to more than 50,000 acres in size is 50 percent contained as of Friday morning, fire officials said.
The Legion Lake Fire sparked Monday in the Black Hills near where U.S. Highway 16A and South Dakota Highway 87 North intersect. It has consumed 53,875 acres, forcing evacuations -- which have since been lifted -- and causing the park to be shut down.
Officials said overnight temperatures dropped down to 12 degrees, halting the progress of the fire, though warmer temperatures in the 50s Friday were expected to keep the blaze "active." They said containment was expected to increase later in the day.
"Mop up and patrolling operations will continue all around containment lines of the fire, including the Blue Bell Lodge area, State Game Lodge area, south along Highway 87, and east past the Custer State Park boundary along the west side of Highway 79," a release from Custer State Park Fire Information said.
The Rapid City Journal reported the cause of the fire was a fallen power line. The newspaper said the Legion Lake Fire was the third-largest fire in modern Black Hills history.