Image copyright US Navy Image caption The MH-53E Sea Dragon is used to search for seaborne mines and also for heavy-lift missions

Two of four crew members rescued after a US Navy Helicopter crashed off Norfolk, Virginia, have died, officials say, while a fifth is still missing.

The US Navy MH-53E Sea Dragon was on a routine training mission.

US Coast Guard officials said they responded to a downed aircraft report at about 11:00 (16:00 GMT).

In a bizarre coincidence, the incident came a day after another US military helicopter crashed in the county of Norfolk, England, killing four people.

The helicopter involved in Tuesday's crash in the UK was a HH-60G Pave Hawk helicopter that belonged to the US Air Force.

Naval Station Norfolk

The aircraft in Wednesday's incident went down 18 nautical miles (33km) east of the Virginia coast. The cause of the crash is not yet known.

Two of the four people rescued and flown to a local hospital later died.

Petty Officer David Weydert said that the missing fifth person was still being sought.

The Coast Guard cutter Shearwater and two MH-60S helicopters are taking part in the search.

The downed helicopter was assigned to Helicopter Mine Countermeasures Squadron 14 (HM-14), the commander of Naval Air Force Atlantic said in a statement.

Norfolk, Virginia, is an important hub for the US military, and is home to Naval Station Norfolk, the largest naval complex in the world.

The water temperature there is about 6C (42F), according to US weather officials.

The helicopter is typically used in deliveries and in mine countermeasures.

The same model of helicopter crashed in 2012 in Oman, killing two Navy crew members.