Three men have died and a 5-year-old boy was left with a broken arm after a car drove off a cliff in the NSW Upper Hunter region on Monday.

Emergency services were called to a property in Gundy, near Scone, at around 5pm when the car was found by a neighbour.

Police said the car drove to the property on Waverley Road on Monday morning, when it is believed it drove off the cliff and rolled down an embankment.

All four people on board were ejected, police said.