A U.S. Coast Guard helicopter crashed in the deep waters of Oahu. The crash killed three people on board and left a fourth one missing. Rescue crews tried to find him or his body on Friday and Rear Adm. Manson Brown, 14th Coast Guard District commander said that "this is a very difficult case because rescuers are being rescued."

The Coast Guard HH-65 Dolphin helicopter crashed in the ocean water of Oahu on Thursday night while it was conducting search and rescue operations with a 47-foot motor lifeboat. The searches during the night didn’t give any result, as the Coast Guard Petty Officer Luke Clayton stated.

The HH-65 Dolphin went down at about five miles south of Honolulu International Airport at about 8:15 p.m. The people on board the lifeboat and passengers on an Air Force C-17 transport aircraft that was passing by saw the crash.

The firefighters in Honolulu pulled the three crews members from the water and took them to the Queen’s Medical Center, but they were later pronounced dead. Co-pilot Lt. Cmdr. Andrew Wischmeier, rescue swimmer Petty Officer 1st Class David Skimin and flight mechanic Petty Officer 2nd Class Joshua Nichols, according to the Coast Guard were the victims but the authorities didn’t release the name of the missing crew member.

"Coast Guard missions — even training missions — are inherently dangerous, and this aircrew was performing a drill in the weather conditions we are called into when we rescue others. It's a terrible loss," a Coast Guard spokesman said.

The HH-65 Dolphin was made by Aerospatiale and is 44 feet long. The helicopter was made to carry a pilot, co-pilot, flight mechanic and rescue swimmer, but it is not capable of doing water landings.