Two Marine Corps helicopters crashed off the Hawaiian island of Oahu late Thursday night. Rescue crews are currently searching for the 12 passengers aboard the two helicopters.

The Marine Corps confirmed this morning that there is a search ongoing for the passengers of the two CH-53 helicopters. Each aircraft had six people aboard, Coast Guard Chief Petty Officer Sara Mooers told The Associated Press. A Coast Guard helicopter and airplane did arrive at the scene, which was two and a half miles offshore after midnight. They located the debris field.

Hawaii News Now reports that Mooers said a Waialua resident saw a fireball, while another said that there was a flare. The Coast Guard believes that the two helicopters collided.

“Crews discovered a life raft with no one on board and visible flames on the water,” Mooers told HNN.

It’s still not clear what the two helicopters were doing in the area and the MArine Corps would not provide more details.

The search for survivors will get progressively more difficult Friday, as the surf off Oahu’s NortH shore is expected to be at least 35 feet high.