A medical transport helicopter crashed into the sea in southwestern Japan, killing a doctor, a patient, and the patient’s caretaker.

Three survivors—pilot Hiroshi Hamada, mechanic Kazuto Yoshitake, and nurse Sakura Kunitake—were rescued with hypothermia but conscious.

The helicopter was en route from Nagasaki to a Fukuoka hospital, the Associated Press has reported.

The cause of the crash is under investigation.

Written by B.C. Begley