Authorities have declared a state of emergency on the Greek island of Chios after a forest fire fanned by high winds threatened homes overnight.

The Fire Service and local officials said elderly residents in several villages in the southwest of the island had been moved out of their homes in a precautionary evacuation after the fire broke out before dawn Monday.

Six fire-fighting helicopters were operating in the area, but strong winds kept planes grounded. The blaze is affecting areas associated with producing mastic gum — a popular local product used mainly to add flavor in cooking and made from tree sap.