ATHENS, Greece -- A major wildfire is burning out of control for a fourth day on the eastern Aegean island of Chios, ravaging forests and agricultural lands, including the island's famed mastic trees.

About 360 firefighters, soldiers and volunteers have been battling the blaze, which broke out shortly after 2 a.m. Saturday. Authorities estimate that by Tuesday it had destroyed about 12,000 hectares of forest and farmland.

Chios is famous for the production of mastic, a gum-like resin with a distinctive flavor produced only by trees on certain parts of the island. It is used widely in confectionery, cooking and cosmetics and a major source of income.

Summer forest fires are common in Greece, and the country has seen dozens of blazes in recent weeks following a heat wave.