BILLINGS, Mont. (AP) — A single-engine airplane crashed in the northern part of Yellowstone National Park, seriously injuring the 54-year-old pilot. Gardiner resident Bill Hill tells the Livingston Enterprise he heard a plane's engine struggling at about 8:30 a.m. Monday and saw the small plane headed toward the ground at a weird angle. Hill says he was first on the scene and saw pilot Mark Nardin of Pray crawl out of the wreckage. He says Nardin had his wits about him, complained about pain in his ribs and appeared to have a broken leg. Hill says he stayed with Nardin until emergency responders arrived. Yellowstone spokesman Al Nash said the pilot was taken to the hospital in Bozeman. The National Transportation Safety Board is investigating the crash.