Updated 6:06 PM EST
Efforts to locate the 12 Marine crewmembers of two CH-53E Super Stallions believed to have collided during routine night training have been continuing for more than 12 hours in the area, where it's nearly 1p.m. local time.
Capt. Timothy Irish, a spokesman for III Marine Expeditionary Force said the Marines were alerted to a possible incident at 11:38p.m. last night, when the two aircraft from Marine Heavy Helicopter Squadron 463, out of Marine Corps Base Hawaii, failed to check in on time.
Carr said the Coast Guard was first alerted to a problem when two civilians on the beach separately reported seeing a fireball and a flare.
Coast guard assets including an MH-65 Dolphin rescue chopper, a C-130 Jet and two cutters continue to patrol a seven-mile debris field. Two Navy guided missile destroyers, the Gridley and the John Paul Jones, are assisting in the effort, as are Honolulu rescue teams and Marines from the nearby base.
Nothing has been recovered from the debris field yet, Carr said, but the wreckage is consistent with a military aircraft.
Breaking surf up to 40 feet high is adding to the challenge of searching for survivors.
"It's very difficult to find things right now," he said.
The Marines aboard the two helicopters included several instructor-trainers in addition to the standard four-man crews, Irish said. They were conducting routine night training that was to start and end at Marine Corps Base Hawaii.
Marine investigators are still investigating the cause of the crash, Irish said. He noted that there were no early indications that anything was amiss with the aircraft or the planned flight. "This was preplanned and routine nighttime flying," he said. "The squadrons were based here; they know the course … Nothing that I've seen personally that was out of the ordinary."
Updated 4:20 PM EST
As of 4p.m. Eastern time, the search continues amid stormy conditions for survivors of a helicopter crash involving two CH-53E Super Stallions that collided during night training.
Coast Guard personnel are searching in a debris field approximately seven miles off the north shore of Oahu, an area that stretches from Mokule'ia Beach to Turtle Bay, Marine Corps spokesman Maj. Chris Devine said in a news release. The search-and-rescue teams are grappling with high winds and choppy waves as they continue to patrol the region.
Officials said the winds are reaching speeds of 17 to 23 miles per hour, with 16-foot wave swells, 30-to-40-foot surf, and one mile of visibility. A high surf advisory is in effect, with swells as high as 30 feet expected later in the day.
"The Coast Guard is asking that people use extreme caution along the coastal area surrounding the wreckage site which stretches from Mokule'ia Beach to Turtle Bay," Lt. Scott Carr, a spokesman for the Coast Guard's 14th district, said in a statement. "We are urging people to stay out of the water and off the beaches due to debris that could pose potential risk and cause serious bodily harm."
An MH-60 helicopter crew from 37th Helicopter Squadron out of Marine Corps Base Hawaii has now joined Coast Guard, Navy and civilian responders in the search, officials said.
Officials with III Marine Expeditionary Force will brief the media in a press conference at noon local time, or 5p.m. Eastern time. The cause of the incident remains under investigation by the Marine Corps, officials said.
A defense official told Military.com that the USS Gridley and the USS John Paul Jones were on scene providing surface search assistance and "lily-pad support" for the search-and-rescue operation. The Gridley's home port is San Diego, Calif., while the John Paul Jones is based at Joint Base Pearl Harbor-Hickam in Hawaii.
Capt. Timothy Irish, a spokesman for III Marine Expeditionary Force, said about 30 Marines from Combat Logistic Battalion 3 and Marine Aircraft Group 24 out of Hawaii had also joined the effort in the last hour to provide logistical support.
"We're sending food, water, electrical equipment and other equipment to help investigators," Irish said.
Marine and Coast Guard officials said they had no new discoveries to report as they continue to search in and around a debris field off Oahu's north shore. No survivors have yet been located.
Officials with the Coast Guard's 14th District in Hawaii said they were notified about two potentially downed aircraft at 11:38 p.m. local time Thursday.
Search and rescue operations located a debris field off the north shore of Oahu, Scott Carr, a Coast Guard spokesman told Military.com. Carr said he could not speak to anything specific that had been found in the debris field, but said that as of 10.a.m. Eastern time, no survivors had been located.
The Coast Guard continues to search the area -- located about 2 1/2 miles off the coast, near the town of Haleiwa -- with an MH-65 Dolphin rescue helicopter and Coast Guard C-130 jet. Two Coast Guard cutters, the Kiska and the Ahi, both from the Honolulu-based 14th district, are en route to assist in search efforts.
Carr said the Honolulu fire and police departments had also assisted in the search effort.
The Marine Corps has identified the unit to which two CH-53E Super Stallion helicopters believed to have crashed off the coast of Oahu are attached.
The choppers are from Marine Heavy Helicopter Squadron 463, Marine Aircraft Group 24, 1st Marine Aircraft Wing, from Marine Corps Base Hawaii, headquartered at Kaneohe Bay.
Officials with Headquarters Marine Corps confirmed the Coast Guard is conducting an active search and rescue operation for the two aircraft, which reportedly collided in flight. Six Marines were aboard each helicopter at the time of the crash.
The aircraft were on a local training mission at the time of the incident, said Capt. Timothy Irish, a spokesman for III Marine Expeditionary Force, out of Hawaii.