ATHENS, Greece — Greek authorities have sent reinforcements to firefighters battling a major forest fire burning out of control in a nature reserve on the island of Evia for a third day, while water-dropping aircraft were trying to extinguish the flames in a hard-to-reach canyon.

A total of 12 water planes, including two sent from Italy and one from Spain, and 11 helicopters resumed flights shortly after dawn Thursday, the fire department said. Around 100 more firefighters were sent overnight, bringing the total to 382.

The fire broke out at around 3 a.m. Tuesday and has ravaged the nature reserve of dense pine forest. Four villages were evacuated on the first day, although some residents returned to their homes on Wednesday.

Forest fires are common in Greece during the hot, dry summer months.