A U.S. navy helicopter went down off the Virginia coast on Wednesday, killing two of its five crew members, the military said. It is the second deadly crash of a U.S. military chopper in as many days, following the loss of an air force Pave Hawk helicopter over the U.K. 

The MH-53E Sea Dragon helicopter was on a training flight when it crashed into the Atlantic Ocean near Fort Story, about 240 kilometres south of Washington, the navy said in a statement.

A nearby coast guard cutter and two helicopters were sent to the site after receiving a distress call at about 10:45 a.m. ET, said Captain Todd Flannery, commander of Helicopter Sea Combat Wing Atlantic, during an online news conference.

Two of the four people rescued and flown to a hospital in Norfolk, Virginia, have died. Of the other two, one is listed in serious condition, the other has been upgraded to fair, the Navy said in a news release.

The fifth crew member is missing. 

"Today has definitely been a tough day on all of us," said Flannery. "Our heartfelt prayers go out to the families and loved ones of those killed and injured in today's crash."

None of the two pilots and three air crewmen has been identified. Flannery said the cause of the crash was under investigation.

The helicopter was part of an anti-mine squadron based at Norfolk, Virginia.

Crash in 2012

In July 2012, two crew members were killed when the same model helicopter crashed into a canyon in the Gulf nation of Oman while lifting a downed aircraft.

According to a navy investigation obtained by The Virginian-Pilot in November, the July 2012 crash of the $50-million helicopter revealed a series of problems within the Sea Dragon program. In that specific crash, the report blamed the crew for skipping preflight safety checks and for failing to develop a concrete plan for how and when to abort the mission.

But Flannery told the newspaper following the investigation that the navy has invested millions of dollars to upgrade and better maintain its remaining 29 Sea Dragon airframes since the crash, including adding more than 100 maintenance personnel to the Norfolk-based squadrons.

The navy had planned to phase them out beginning in the mid-2000s, but kept the Sea Dragons flying because the service had no viable replacement.

With files from Associated Press