A small plane has crashed in the US state of Montana, killing 14 people, including seven children under the age of 10, according to the US Federal Aviation Administration (FAA).

Mike Fergus, an FAA spokesman, said the single-engine turboprop Pilatus PC-12 crashed about 150 metres from the airport in Butte, Montana, while trying to land on Sunday.

Fergus said initial reports showed that there were a number of children on board the plane.

"We think that it was probably a ski trip for the kids," he said.

He said the aircraft had departed from Oroville, California, on a scheduled flight to Bozeman but the pilot had cancelled his flight plan at some point and headed for Butte.

The National Transportation Safety Board and the FAA will be investigating the crash, added Fergus.

The local Montana Standard newspaper, citing witnesses' accounts in an online story, said the plane crashed into a cemetery.

Martha Guidoni, who was at a petrol station across from the cemetery, said the plane "just nose-dived into the ground".