Two recreational helicopters collided over the Gold Coast beach (located in northeastern Australia, 75 km south of Brisbane). The Queensland Ambulance Service said Monday that 13 people were injured.

"Multiple QAS resources and other emergency services are on the scene of a major incident involving two helicopter at 1.59pm. Thirteen patients are being assessed at the scene were two helicopters have collided on Main Beach," the agency said in a statement.

State Police officers are working at the scene and an investigation into the cause of the incident is underway.

At least four people were killed in the collision and nine others suffered varying degrees of injury, Queensland State Police said. According to the agency, three are hospitalized in critical condition. "The investigation is ongoing, there will be a report by police for the coroner, and also the Australian Transport Safety Bureau is leading an investigation," Queensland State Police Inspector Gary Worrell pointed out during a statement to reporters.