(CNN) -- A plane burst into flames after crashing in Alaska's Denali National Park Sunday, officials and witnesses said.
Initial reports indicate the plane crashed around 4:15 p.m. (8:15 p.m. ET), FAA spokesman Allen Kenitzer said.
He said the plane was possibly a four-engine aircraft, but authorities were still gathering information about the crash. There was no word on the fate of those on board.
Jeff Kowalczyk said he was hiking through the park with his wife when he looked up and saw the plane almost upside down as it crashed into the hillside a few hundred yards away.
Kowalczyk, an EMT, said he and his wife, a nurse, rushed to the scene after seeing the military-style cargo plane's plunge. But the crash set the aircraft ablaze, he said, preventing them from getting close.
"The whole experience was really surreal," he said.