(CNN) -- Two sailors have died after the Navy helicopter they were in crashed Wednesday off the southern Virginia coast, the Navy said.
The Coast Guard, Virginia Beach Fire Department and Navy continued Wednesday night to search for another sailor who'd been aboard the fallen aircraft. Two sailors who had been rescued were in stable condition at Sentara Norfolk General Hospital, the Navy said in a statement.
"Today has been a tough day for all of us," said Capt. Todd Flannery, commander of the Navy's Helicopter Sea Combat Wing Atlantic, based in Norfolk, Virginia.
Flannery made that comment late Wednesday afternoon, hours before the Navy announced the second fatality in the crash in ice-cold waters about 18 nautical miles (21 miles) east of Cape Henry.
At the time, he said two injured sailors were stable, while another was preparing to undergo surgery at the Norfolk hospital.
Authorities offered no indication that they knew the missing sailor's whereabouts, with Flannery saying it was possible he or she sunk to the Atlantic Ocean floor inside the crashed MH-53E Sea Dragon.
Speaking then about those aboard two Coast Guard boats among those participating in the search," Coast Guard Capt. John Little said, "They could not see the helicopter, but they are continuing to search."
The Navy helicopter and its five-person crew set off Wednesday morning from Norfolk on what Flannery described as a "routine mine countermeasure operations."
The first apparent sign of trouble came around 10:45 a.m., when the aircraft's crew issued a distress call.
It went down soon thereafter, with a second MH-53E Sea Dragon operating in the same area providing "immediate support," according to Flannery.
Two Navy helicopters assigned to the same 600- to 700-sailor squadron quickly rushed to the scene, spotting four of the sailors "close to the wreckage floating in the water" around 11:15 a.m., Flannery said.
The air temperature was 28 degrees and the water temperature was 41 degrees, with 1- to 2-foot seas, Coast Guard spokesman Nyx Cangemi said.
The sailors were hoisted up two-apiece in two rounds -- the first pair 10 minutes after the rescuers' arrival, and the other set at 11:38 a.m., said the Navy captain. They were quickly transported to the Norfolk hospital. Flannery said he was not sure whether the first confirmed fatality died en route to or at the hospital.
"I saw a big Navy helicopter land here and it landed really quick and fast," Chris Goetz told CNN affiliate WAVY at the hospital. "They took two guys in on the stretchers and immediately took back off and came back maybe five minutes later and had two more guys all on stretchers."
The 87-foot Coast Guard Cutter Shearwater happened to be in the area at the time.
"They did not see the crash -- they were that far away -- but heard it and heard our call for assistance and immediately responded," said Little of the Coast Guard.
That ship is one of four now surveying the scene from water level, along with another Coast Guard and two fire boats from the Virginia Beach Fire Department.
The helicopter was assigned to Helicopter Mine Countermeasures Squadron Fourteen (HM-14), which is based at Naval Station Norfolk Chambers Field.
The MH-53E Sea Dragon carries no weapons. It has two pilots and a crew of one to six, depending on its mission, according to the Navy. There were 31 of the aircraft in operation, it said. Its role includes anti-mine operations.
Flannery didn't detail the information communicated in Wednesday's distress call or what may have caused the helicopter to go down, saying that an investigation board will be looking into that.
But he didn't hesitate when asked whether he had any concerns, generally, about the safety of MH-53E Sea Dragon helicopters in the wake of Wednesday's crash.
"I do not," Flannery said.
CNN's Greg Seaby contributed to this report.