Water safety officials hand over possible debris from an Army UH-60 Black Hawk helicopter crash to military personnel stationed at a command center in a harbor, Wednesday, August 16, 2017 in Haleiwa, HI. An Army helicopter with five on board crashed several miles off Oahu's North Shore late Tuesday. Rescue crews are searching the waters early Wednesday. (AP Photo/Marco Garcia)
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HONOLULU (AP) - The U.S. Coast Guard said Thursday it was now searching up to 50 miles (80 kilometers) off Hawaii for five soldiers missing after their Black Hawk helicopter crashed during nighttime training.
Swift and dynamic currents prompted the rapid expansion. About 24 hours earlier, the search was focused on waters about 5 miles (8 kilometers) off shore.
Chief Petty Officer Sara Muir, a spokeswoman for the Coast Guard in Hawaii, said this is typical for this part of the ocean.
"We're accustomed to that and our search planners are accustomed to that," she said.
The water depth varies across the vast area. At the moment, the Coast Guard is only searching the surface of the ocean.
Rescue crews were looking for two pilots and three crew members missing since their helicopter went down off Oahu's Kaena Point late Tuesday.
Airplanes were scouring the outer edges of the search area, Muir said. Helicopters and vessels were searching closer in, about 15 to 20 miles (24 to 32 kilometers) offshore.
On Wednesday, Honolulu Fire Department search and rescue crews found and collected pieces of helicopter fuselage and a helmet.
Two Black Hawk crews were conducting training between Kaena Point and Dillingham Airfield when communications were lost, officials said.
Kaena is a rugged spot where Oahu's northern and western coasts meet to form a small peninsula. Officials closed the state park at Kaena Point while the search was underway.
A Coast Guard plane, two helicopters and several boats were being used in the search. The Army and Marine Corps joined the effort, as did Honolulu firefighters and lifeguards.
The two helicopters are part of the 25th Combat Aviation Brigade based in Hawaii.
The UH-60 Black Hawk is a four-bladed, twin-engine utility helicopter manufactured for the Army by Sikorsky Aircraft starting in the 1970s.
More than 3,000 Black Hawk aircraft are in service around the world, according to Sikorsky's parent company Lockheed Martin. The U.S. Army owns 2,300 of them.
In April, one crew member was killed and two others were injured when an Army Black Hawk helicopter crashed onto a golf course in Maryland during a routine training flight.
In 2015, 11 crew members were killed when an Army Black Hawk helicopter crashed into the water off Eglin Air Force Base in Florida.
In this photo released by the U.S. Coast Guard, a Response Boat-Medium boat crew from Coast Guard Station Honolulu conducts a search for five crew members aboard a downed Army UH-60 Black Hawk helicopter approximately two miles west of Kaena Point, Oahu, Hawaii, Wednesday, Aug. 16, 2017. A multi-agency team scoured the ocean off Hawaii on Wednesday for the soldiers aboard the Army helicopter that went down during a nighttime training exercise. (Petty Officer 2nd Class Tara Molle/U.S. Coast Guard photo via AP)
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In this photo released by the U.S. Coast Guard, a UH-60 Black Hawk helicopter aircrew from Wheeler Army Airfield and a fireboat crew from the Honolulu Fire Department conduct a search for five crew members aboard a downed Army UH-60 Black Hawk helicopter approximately two miles west of Kaena Point, Oahu, Hawaii, Wednesday, Aug. 16, 2017. A multi-agency team scoured the ocean off Hawaii on Wednesday for the soldiers aboard the Army helicopter that went down during a nighttime training exercise. (Petty Officer 2nd Class Tara Molle/U.S. Coast Guard via AP)
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Investigators examine materials at a command center Wednesday, Aug. 16, 2017, in Haleiwa, Hawaii. An Army helicopter with five on board crashed several miles off Oahu's North Shore late Tuesday. (AP Photo/Marco Garcia)
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Water safety officials hand over materials to military personnel stationed at a command center at a boat harbor, Wednesday, Aug. 16, 2017, in Haleiwa, Hawaii. An Army helicopter with five on board crashed several miles off Oahu's North Shore late Tuesday. (AP Photo/Marco Garcia)
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Honolulu ocean safety lifeguards on jet skis hand over materials to military personnel stationed at a command center at a boat harbor, Wednesday, Aug. 16, 2017, in Haleiwa, Hawaii. An Army helicopter with five on board crashed several miles off Oahu's North Shore late Tuesday. (AP Photo/Marco Garcia)
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US Coast Guard personnel stand near a USCG mobile command vehicle near a boat harbor, Wednesday, Aug. 16, 2017, in Haleiwa, Hawaii. An Army helicopter with five on board crashed several miles off Oahu's North Shore late Tuesday. Rescue crews are searching the waters early Wednesday. (AP Photo/Marco Garcia)
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Military personnel gather around the Honolulu Fire Department Command Center at a boat harbor, Wednesday, Aug. 16, 2017 in Haleiwa, Hawaii. An Army helicopter with five on board crashed several miles off Oahu's North Shore late Tuesday. Rescue crews are searching the waters early Wednesday. (AP Photo/Marco Garcia)
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Lt. Col. Curt Kellogg, spokesperson for the 25th Infantry Division, second from left, speaks at a news conference discussing the Army UH-60 Black Hawk helicopter crash Wednesday, Aug. 16, 2017 in Haleiwa, Hawaii. The Black Hawk with five on board crashed several miles off Oahu's North Shore late Tuesday. Rescue crews are searching the waters early Wednesday. Also pictured, Lt. Scott Carr, of the US Coast Guard's 14th District, left, Capt. David Jenkins, spokesperson for the Honolulu Fire Department, second from right, and Lt. John Hoogesteden, of Honolulu Ocean Safety, right. (AP Photo/Marco Garcia)
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Honolulu Fire Department search and rescue members sit on a docked boat at a boat harbor, Wednesday, Aug. 16, 2017, in Haleiwa, Hawaii. An Army helicopter with five on board crashed several miles off Oahu's North Shore late Tuesday. Rescue crews are searching the waters early Wednesday. (AP Photo/Marco Garcia)
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The Honolulu Fire Department Command Center is mobilized at a boat harbor, Wednesday, Aug. 16, 2017, in Haleiwa, Hawaii. An Army helicopter with five on board crashed several miles off Oahu's North Shore late Tuesday. Rescue crews are searching the waters early Wednesday. (AP Photo/Marco Garcia)
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CORRECTS TO WAIALUA, NOT MOKULEIA - Honolulu Fire Department members gather at the entrance of Kaena Point, Wednesday, Aug. 16, 2017 in Waialua, Hawaii. An Army helicopter with five on board crashed several miles off Oahu's North Shore late Tuesday. Rescue crews are searching the waters early Wednesday. (AP Photo/Marco Garcia)
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CORRECTS TO WAIALUA, NOT MOKULEIA - A Honolulu firefighter stretches caution tape across the entrance of Kaena Point, Wednesday, Aug. 16, 2017 in Waialua, Hawaii. An Army helicopter with five on board crashed several miles off Oahu's North Shore late Tuesday. Rescue crews are searching the waters early Wednesday. (AP Photo/Marco Garcia)
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The Honolulu Fire Department Command Center is seen at a boat harbor, Wednesday, Aug. 16, 2017 in Haleiwa, Hawaii. An Army helicopter with five on board crashed several miles off Oahu's North Shore late Tuesday. Rescue crews are searching the waters early Wednesday. (AP Photo/Marco Garcia)
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