CH53 transport helicopter
A CH53 transport helicopterGetty

The US Coast guard has identified a debris field off the coast of Hawaii as it searches for missing passengers and crew after two helicopter crashed in mid-air.The US Marine Corps has confirmed the start of an active search for the pair of 2 CH-53's off the coast of Oahu.

Hawaii News Now reported residents in Wailua, near where the helicopters fell, described seeing a fireball in the immediate aftermath of the collision at roughly 11:40 pm on 14 January. An emergency flare appeared to have been fired shortly after the debris hit water near Haleiwa.

The rescue effort to retrieve the missing personnel from the Marine corps includes the Coast Guard, the Honolulu Fire Department and the US Navy, as well as the Marine Corps itself. Coast Guard Chief Petty Officer Sara Mooers confirmed to local media that each aircraft had six people aboard. "Crews discovered a life raft with no one on board and visible flames on the water," she added.

An MH-65 Dolphin helicopter and a HC-130 aircraft have been dispatched to assess the wreckage. Two Coast Guard Cutters are also due to arrive at the debris field which lay initially half a mile offshore. A high swell around the pacific state has meant the debirs has moved 8 miles offshore.

It not is immediately clear whether any survivors had been found or what caused the two aircraft to collide with each other and why early warning systems failed.