Three US Marines have died and five more have been seriously injured in a crash during a military aircraft training exercise near Darwin on Sunday.

The aircraft, a MV-22B Osprey, crashed on the Tiwi Islands at approximately 9.30am. The cause of the incident still unknown.

The MV-22B Osprey aircraft was “transporting troops during a routine training exercise” when it crashed on Melville Island with 23 personnel on board.

The marines were part of the Marine Rotational Force (MRF), which is located in Darwin.

“There was a total of 23 personal on board. Three have been confirmed deceased while five others were transported to Royal Darwin Hospital in serious condition,” the MRF said.

“Recovery efforts are ongoing. The cause of the incident is under investigation.”

The MRF was established under the Gillard Government in 2011 and has been deployed every year. The force currently consists of over 2,500 Marines.

Photo: V-22 Osprey by Peter Gronemann available HERE and used under a Creative Commons license. This image has not been modified.