Four of five rescued from downed chopper

Four people have been rescued but a fifth is still missing after a US Navy helicopter went down in the Atlantic, the Coast Guard says.

Four of five people aboard a US Navy helicopter that went down in the Atlantic have been rescued. (AAP)

Four of five people aboard a US Navy helicopter that went down in the Atlantic off Virginia have been rescued.

The search is continuing for the fifth person, while two Coast Guard cutters head to the scene.

A Navy helicopter rescued the four, but their conditions are not known, the Coast Guard said on Wednesday.

The helicopter has been identified by the Navy as an MH-53-E.

According to the Naval Air Systems Command website, the aircraft performs airborne mine countermeasures and on board delivery missions.