CAMP PENDLETON -- A Navy sailor died and three others are missing after a Navy Seahawk helicopter crashed off the coast of Camp Pendleton on Friday afternoon during search and rescue training. Military search teams were looking for more survivors through the night, a Navy commander said.

View A Video

The MH-60S Seahawk chopper crashed about 2:30 p.m. 50 miles offshore near San Clemente Island while training near the USS Bonhomme Richard, Navy Cmdr. Jack Hanzlik said. MH-60S helicopters are designed to carry at least 20 troops.

No other aircraft were involved, but another in the area responded immediately and was able to rescue one sailor. It was unclear what may have caused the crash Friday.

"We remain hopeful and put forth all our efforts to find all our friends (from the helicopter)," said Hanzlik at a news conference Friday night at Naval Air Station North Island. "Our biggest fear for them is that the water is cold."

Hanzlik said they will continue looking as long as necessary . He said the crew members train for these kind of incidents and would be wearing flotation vests that include survival equipment such as a communications radio, a whistle, a flare and a flashlight. They also have reflective strips on their helmets, which would be the highest point in the water, in the event they were unconscious and unable to signal for help, Hanzlik said.

Search and rescue crews are hopeful that "they are on the ocean surface, and we just haven't been able to find them," he said. A National Weather Service forecaster said the ocean temperature was approximately 58 degrees Friday.

The Navy helicopter was attached to Helicopter Sea Combat Squadron 23 and was doing routine training in support of Expeditionary Strike Group 5, Amphibious Squadron 7 and the 13th Marine Expeditionary Unit at the time of the crash. Hanzlik said he did not know what phase of flight they were in except that they were not trying to land or take off at the time.

The new squadron, which was commissioned last fall, does search and rescue missions, anti-submarine and anti-surface warfare, logistics support, and works with special Navy teams such as the SEAL teams.

Hanzlik said the helicopter pilot was able to get a mayday off to let others know that they were experiencing problems and were going into the water just before the impact. He said it was unclear if the pilot was specific about the trouble.

Another MH-60S chopper likely used a search and rescue swimmer to go into the water and put the sailor into a hoist, Hanzlik said. The sailor was then flown to the USS Bonhomme Richard amphibious assault ship, which has extensive hospital equipment, but later died.

Search and rescue crews were looking for the other three crew members in inflatable boats and using nearby aircraft, including search and rescue helicopters, until about 6:30 p.m. when the helicopters were called off for safety reasons, Hanzlik said. The U.S. Coast Guard is also assisting. By evening, there were five Navy vessels in the search, the USS Chung Hoon guided missile destroyer, USS Chosin guided missile cruiser, USS Milius guided missile destroyer, and USS Rushmore amphibious vessel, and the Bonhomme, Hanzlik said.

The location of the downed chopper in the water was known but Hanzlik said they did not have any plans to recover it at this time. He said they would not seek to recover it if it was in too deep of water or if there was no value in recovering it. There was no indication whether the missing personnel may still still be on board.

The names of the two U.S. Navy pilots and two crew members are being withheld pending notification of family. Their names will not be released until 24 hours after the family has been notified, Hanzlik said.

The MH-60S Seahawks were first put into use in 2002 and are the Navy version of the Army Blackhawk helicopters. The MH-60S Seahawks can lift loads of up to 6,000 pounds and can fly two hours without refueling, according to military Web site information.

Hanzlik said he did not have statistics readily available on how many crashes had occurred involving MH-60S Seahawks.

On December 9, 1999, a Navy CH-46 Sea Knight helicopter carrying 18 Marines from the USS Bonhomme Richard to the USNS Pecos crashed during a routine training mission into the ocean off Point Loma. Eleven Marines were rescued within minutes of the crash, but six Marines and one Navy corpsman died.

Contact staff writer Yvette Urrea at (760) 901-4076 or yurrea@nctimes.com.