Two helicopters collided during a flight near Australia’s so-called Gold Coast on Monday, killing four people and injuring three seriously, Agerpres reported, citing AFP.

An investigation has been launched to determine the cause of the accident, which occurred on the popular beach of the Gold Coast in the south-east of the Australian region of Queensland.

Television footage showed the helicopter’s propellers on a sandbar off the Gold Coast. A helicopter overturned on the sand nearby, ABC public channel reports.

The other plane appears largely intact at the crash site, which is near Sea World.

The two cars “collided”, one crashed and the other landed “on a sandy beach next to Sea World”, Queensland Police Inspector Gary Worrell said. The collision happened before 2:00 p.m., when the authorities were alerted.

The exact cause of the collision is unknown, but Worrell said it appears one helicopter was about to take off when the other landed.

The helicopter that managed to land lost its windshield, while another crashed and overturned, Agerpres reported, police said.