Seventeen people have died in a plane crash in the American state of Montana.The small, single-engine plane crashed into a cemetary as it was approaching an airport in the town of Butte. There were no surviving passengers. Several children were among those on board. A US aviation official said the plane was probably taking them on a skiing trip. An eyewitness told reporters she saw the plane nosedive straight into the ground. The impact left a crater six metres deep. It’s not yet known what caused the crash.