Two Malaysian Navy helicopters collided in mid-air while flying in formation during a military parade rehearsal, killing all 10 crew members on board.
Footage published by local media showed that one of the two planes collided with the other's propeller before crashing on the ground.
The accident occurred at 09:30 local time (02:30 GMT) in the Malaysian town of Lumut, which is home to a Royal Malaysian Navy base.
There are no known survivors.
“All the victims were confirmed dead at the site and the remains have been sent to the hospital [Lumut] “Military hospital for identification,” the Royal Malaysian Navy said.
She added that she would form a committee to investigate the causes of the accident.
One of the helicopters, a HOM M503-3 with seven people on board, is believed to have crashed on the running track.
The other plane, a Fennec M502-6, which was carrying the other three victims, crashed into a nearby swimming pool.
The state Fire and Rescue Department said it was alerted to the incident at 09:50 local time (01:50 GMT).
“The nation mourns the heart-wrenching tragedy,” Malaysian Prime Minister Anwar Ibrahim said in a post on X, formerly known as Twitter.
He added: “Our condolences to all the families of the victims and our prayers for strength to confront this disaster.”
In March, a Malaysian Coast Guard helicopter crashed into the sea off the Malaysian island of Angsa during a training flight.
Fishermen found and rescued the pilot, his co-pilot, and two passengers on board the plane.