Four people have been killed after a medical helicopter crashed while airlifting a patient to hospital.

According to reports the patient, the helicopter's pilot, a nurse and a medic were all killed in the crash in Alabama on Saturday.

NBC News said the medical flight had been responding to a car accident when the Eurocopter AS350 came down in a wooded area and the Red Cross confirmed there had been "no survivors".

The National Transportation Safety Board are investigating the crash to try and establish why the helicopter came down.