The U.S. Coast Guard says it has responded to a report of a military aircraft collision involving two Marine helicopters off the north shore of Oahu, Hawaii, Chief Petty Officer Fara Mooers told ABC News. 
 
 Responders are searching for 12 people in a debris field 2 miles off the coast of Haleiwa. Each helicopter was carrying six people. 
 
 The Marine Corps said in a news release that the aircraft were from the 1st Marine Aircraft Wing from Marine Corps Base Hawaii. 
 
 The Coast Guard received a call from the Marine Core Air Station, Kane’ohe Bay, at 11:38 p.m. local time Thursday requesting assistance. 
 
 Department of Defense 
 
 Officials launched Coast Guard aircraft -- a MH65 helicopter and an HC130 Coast Guard airplane -- from Oahu. 
 
 The Coast Guard is searching the debris with assistance from a Navy helicopter crew and the Honolulu Fire Department with a helicopter and rescue boat on scene. 
 
 They have not located any personnel at this time and are continuing to search. 
 
 This latest incident follows a string of deadly training exercises for the military. 
 
 Just last month, two Army pilots from Fort Campbell were killed when their AH-64D Apache helicopter crashed during a routine training exercise. That helicopter was found in a rural community. 
 
 In March of 2015, a military training accident caused the death of 11 veteran Marines and soldiers. They were conducting a training mission off the Florida coast when their UH-60 Black Hawk helicopter crashed, killing all on board during a nighttime operation in foggy conditions. ||||| (CNN) Crews are searching for 12 Marines missing at sea after two CH-53 helicopters apparently collided during an overnight training flight off the Hawaiian island of Oahu, authorities said. 
 
 Personnel from the U.S. Coast Guard, Navy, and Honolulu Fire Department looked for survivors seven miles offshore in increasingly poor weather conditions. Swells reached 16 feet, surf rose to 40 feet and visibility extended to only one mile, the Coast Guard said. 
 
 "The weather is making it very difficult," Coast Guard spokesman Lt. Scott Carr told reporters. "It is very difficult to find things right now. 
 
 "Our goal is to find survivors," he said. 
 
 Reported missing 
 
 Loved ones have identified to CNN three Marines missing in the crash, and a CNN affiliate has reported on a fourth missing Marine. 
 
 The family of Captain Kevin Roche told CNN that he is among the 12 Marines missing in the Hawaii helicopters collision. 
 
 Anthony Kuenzel told CNN that his brother-in-law, Capt. Kevin Roche, is among them. The family described him as a passionate Marine and thanked people praying for his safe return. 
 
 "We believe the Marines and Coast Guard are doing everything they can to bring Kevin and his fellow Marines home safely and we are grateful to everyone involved in the rescue," Roche's family said in a statement. 
 
 Loved ones have reported Maj. Shawn Campbell and Cpl. Matthew Drown missing after the Hawaii helicopter crash. 
 
 Maj. Shawn Campbell, 41 was in the collision, said his mother, Donna McGrew, of Houston. A Marine officer visited her at home to brief her. Campbell has a wife and four children, and has done three tours of duty in the Middle East. 
 
 "My heart just breaks, there are 11 other families going through this now. God bless them," McGrew said. 
 
 Another Texan, Cpl. Matthew Drown, was on board one of the helicopters and is missing, his brother Sean Drown told CNN. 
 
 Cpl. Drown, 23, has been in the Marines for five years, and joined shortly after high school. 
 
 Surfers beware 
 
 The search is taking place off the north shore of Oahu, a popular surfing destination. Surfers should avoid any debris in the water, Carr said. Searchers have already spotted floating pieces of debris consistent with military aircraft. 
 
 "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," Carr 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," he added. 
 
 Marine Commandant Gen. Robert B. Neller expressed hope. 
 
 "Thoughts & prayers are with our Marines & their families in Hawaii as search efforts continue. We remain Semper Fidelis," Neller tweeted. 
 
 Thoughts & prayers are with our Marines & their families in Hawaii as search efforts continue. We remain Semper Fidelis @usmc @USNavy @USCG — Robert B. Neller (@GenRobertNeller) January 15, 2016 
 
 Earlier, searchers spotted a fire and debris field, including an empty life raft, about 2½ miles north of Haleiwa Beach, according to Coast Guard Chief Petty Officer Sara Mooers. 
 
 The two helicopters were believed to have collided late Thursday, Mooers said. The Coast Guard received notice at 11:38 p.m. local time. 
 
 The two aircraft apparently didn't issue a mayday call, Carr said. 
 
 Rather, a civilian on the beach first notified authorities of seeing a fireball, followed by a second person reporting a flare, Carr said. 
 
 A Marine Corps CH-53E Super Stallion 
 
 Marine officials contacted the Coast Guard about the missing aircraft around 11 p.m. (4 a.m. Friday ET), Mooers said. A Coast Guard helicopter arrived shortly after midnight (5 a.m. ET), according to the agency. 
 
 CNN affiliate KHON in Hawaii reported that witnesses said they heard a loud boom over the water and saw a flash in the sky. 
 
 Six people were on board each of the two heavy-lift transport helicopters, according to Mooers. 
 
 The missing aircraft are assigned to Marine Heavy Helicopter Squadron 463, Marine Aircraft Group 24, 1st Marine Aircraft Wing, the Marines tweeted. 
 
 According to the unit's website, it is stationed at Marine Corps Naval Air Station Kaneohe Bay, on the opposite side of the island from where the apparent collision occurred. 
 
 The aircraft are from Marine Heavy Helicopter Squadron 463, Marine Aircraft Group 24, 1st MAW in Hawaii. pic.twitter.com/Gn4VmXOIgM — U.S. Marines (@USMC) January 15, 2016 
 
 Participating in the search Friday were two Navy warships, Coast Guard Cutters Ahi and Kiska, a MH-65 Dolphin helicopter, a HC-130 Hercules airplane, a MH-60 helicopter, Honolulu Fire Department crews, and a helicopter rescue boat, officials said. 
 
 A high surf advisory is in effect for the north facing shore of Oahu where the search is being conducted, authorities said. 
 
 The Marine Corps are investigating the cause of the accident.
– Twelve people are missing after two US military helicopters collided off the coast of Hawaii's Oahu island, reports ABC News. Coast Guard and Navy search teams have spotted the debris field—including an empty life raft—about 2 miles off the coast, reports the network and CNN. The first call of the crash came in at 11:38pm Thursday, and each of the helicopters had six people aboard.