CUSTER, S.D. (AP) — A wildfire in a popular South Dakota state park grew rapidly overnight, pushing beyond the park's borders and threatening nearby communities, officials said Wednesday. The fire in Custer State Park, which is just south of Mount Rushmore in the state's southwest, grew from about 6 square miles (16 square kilometers) on Tuesday to about 55 square miles (142 square kilometers) on Wednesday and is 7 percent contained, the park said in a news release. "From hearing the briefing this morning, a lot of these firefighters say they haven't seen anything like this fire in 10 to 20 years," said Kobee Stalder, the park's visitor services program manager.