Taiwan authorities said that the rescue operation continues Tuesday morning.
According to local reports, the UH-60M Black Hawk helicopter took off Monday night from Taitung to the island of Lanyu for medical aid service. On its way back, it disappeared.
The six on board consisted of three crew members, a patient, a family member and a nurse.
Another family member of the patient who saw the aircraft take off at the airport said that the helicopter flew about three minutes after takeoff when the nose of the helicopter started to dip, and soon the flight light faded away.