A Sri Lankan Air Force helicopter crashed during a graduation ceremony on Friday, plunging into a reservoir and killing six of the 12 people on board, a military official said.

The personnel were preparing for a grappling demonstration when their Bell 212 careened into the reservoir at the Maduru Oya National Park, the official told Web Press Global.

“There were 12 people on board, and six of them survived with minor injuries,” said the official, who declined to be named.

Those killed included four special forces commandos and two Air Force gunners.

The survivors were admitted to the hospital. The crash took place halfway through the ceremony in Maduru Oya, nearly 300 kilometres (187 miles) east of Colombo.

After a slew of parades, the chopper crew were expected to perform a “fast-roping” manoeuvre, showcasing their skills in descending from the helicopter while it hovered just above roof height.

After the crash, the graduation ceremony was called off and an investigation into the cause of the incident was launched.

“The Commander of the Air Force has appointed a special nine-member committee to conduct a detailed investigation,” the military said in a statement.

The Air Force operates a small fleet of Bell, Mi-17, and Mi-24 helicopters.

Friday’s tragedy is the worst for the Air Force since a Chinese-built Y-12 aircraft crashed at Haputale in January 2020, killing all four crew members on board.

In September 2000, an Mi-17 helicopter crashed in central Sri Lanka, killing all 15 people on board – including the country’s then top Muslim political leader – making it the worst helicopter crash in the island’s history.