Lisbon, August 31- A tragic helicopter crash in Portugal's northern Douro River region claimed the lives of at least four people, with one person still missing. The helicopter, engaged in firefighting operations, crashed around 12:30 PM local time on Friday while returning from extinguishing a fire on the island of Bajao.

According to Reuters, the Portuguese government has declared a national day of mourning on Saturday in honor of the victims. Commander Rui Silva Lamperia of the National Naval Authority reported that the helicopter's pilot survived the crash with minor injuries. Rescue teams have recovered two bodies from inside the helicopter and two more from its tail section, while efforts continue to locate the missing fifth passenger.

The deceased were members of the Emergency Protection and Rescue Unit, aged between 29 and 45 years. The pilot, a 44-year-old civilian, was fortunate to survive with only minor injuries.

Authorities have launched an investigation to determine the cause of the crash. The incident has deeply affected the country, highlighting the dangers faced by those combating wildfires in challenging conditions.