SANTIAGO, CHILE - Chile declared a state of emergency Friday as more than a dozen wildfires that have scorched nearly 50,000 hectares (123,500 acres) threatened to encroach on towns, factories and vineyards.

Firefighters, forestry service personnel and members of the military were battling 18 separate blazes in the center and south of the country that have been fueled by strong winds and a heat wave.

The largest has consumed 24,000 hectares in and around Pumanque, a rural area 140 kilometers (87 miles) south of the capital, Santiago, that is near some of Chile's vineyards.

"I've instructed the Interior Ministry to declare a catastrophe zone and a state of emergency in the areas affected by the fires," President Michelle Bachelet said on Twitter.

The smoke from the blazes cloaked Santiago in a thick haze. Television news images showed helicopters and planes trying to douse the out-of-control fires, apparently to little avail.

The head of Chile's CONAF forestry service, Aaron Cavieres, said the fires were caused by humans, but that it could not be determined whether they were set intentionally.

CONAF said it would close access to all national parks between the northern Coquimbo and south-central Biobio regions until Sunday. While several fires are in the vicinity of some of Chile's national parks, none have been directly affected.