Media playback is unsupported on your device Media caption Investigators are trying to determine what caused the crash, as Wendy Urquhart reports

A private jet has crashed into a house in a suburb of Washington DC, killing three people on board and three on the ground, fire officials say.

The small plane came down in Gaithersburg, Maryland, on Monday, setting two other homes on fire.

Witnesses told local media that the plane seemed to be struggling to maintain altitude before it crashed.

A Federal Aviation Administration spokeswoman said the jet was trying to land at a nearby airfield.

The Embraer Phenom 100 twin-engine plane crashed about one mile (1.6km) from the Montgomery County Airpark, Montgomery county fire department spokesman Pete Piringer told reporters.

A mother and two children in the home hit by the plane who were initially reported as missing have now been confirmed as dead, officials said.

The house was nearly completely destroyed. The two other homes also had significant damage.

Neighbour Fred Pedreira told the Associated Press he had seen the plane coming down.

"He was 90 degrees - sideways - and then he went belly-up into the house and it was a ball of fire," he said.