An Alabama father and his two daughters were found dead after their small plane crashed in the Bob Marshall Wilderness area of Montana. The Bob Marshall Wilderness Area is located in western Montana, primarily within the Rocky Mountains. It spans parts of Flathead County, Lewis and Clark County, and Powell County. It lies south of Glacier National Park and west of the Continental Divide. It’s remote and largely inaccessible by road

According to the Powell County Sheriff’s Office, the crash was first reported around 4:30 p.m. local time on Friday, Oct. 17. Search crews from Malmstrom Air Force Base in Great Falls began looking for the aircraft and continued through midnight, PEOPLE reported.

The following morning, at about 9 a.m. on Saturday, Oct. 18, a volunteer aircraft with the Montana Department of Transportation Aeronautics Division located the wreckage in northern Powell County. The scene was then turned over to the U.S. Air Force, which also had helicopters assisting in the search. The pilot and two passengers were pronounced dead at the site.

Authorities said the investigation has been handed over to the Federal Aviation Administration (FAA) and the National Transportation Safety Board (NTSB) to determine what caused the crash.