A helicopter crashed into the Douro River in northern Portugal on Friday, resulting in the deaths of at least four people.

The pilot was the only survivor and was taken to the hospital with injuries, local authorities said.

The helicopter, carrying a team of five specialists from the Emergency Protection and Rescue Unit, was returning from a firefighting mission when the accident occurred. Two bodies were found inside the aircraft, while two others were located near the tail of the plane. One person remains missing.

The cause of the crash is currently under investigation. Portuguese Prime Minister Luís Montenegro has declared tomorrow a day of national mourning. (ILKHA)