Vietnam's defence ministry said on Wednesday that three people died after an army helicopter crashed in the mountainous area south of the country during a training flight.
The Airbus EC 130 T2 helicopter was carrying an instructor and two trainee pilots when it went missing on Tuesday. Reports say the helicopter disappeared from radar 23 minutes after take-off in Ba Ria-Vung Tau province.
"Rescue forces exerted all efforts to locate the helicopter crash on Bao Quan mountain," the defence ministry said in a statement.
"All the three men from the flight training team were found dead," it added.
Rescuers have recovered the bodies of those three military personnel. Authorities said an investigation was underway to find out the cause of the crash.
The safety record of the civilian aviation sector in Vietnam is generally good, but over the past few years there have been several incidents involving military aircraft.
This was the latest incident in a series of deadly military aircraft accidents. In 2016, a total of 14 people have been killed in four military aviation accidents, including this recent crash.
According to the defence experts and arms firms, Vietnam is buying fighter jets, helicopters, surveillance planes radars and surface-to-air missiles as part of a military buildup.