Chile mobilised its military to help evacuate thousands of people from the historic port city of Valparaiso, which is threatened by a forest fire that has already destroyed 500 homes.
President Michelle Bachelet declared a disaster zone as the massive blaze moved in on the city, which has a world heritage site at its centre.
There was no official confirmation of fatalities, but local media said 11 people had died.
While 1,250 firefighters, police and forest rangers battled the blaze, 2,000 Chilean sailors in combat gear patrolled streets to maintain order and prevent looting.
More than 10,000 people have so far been evacuated from the hills above Valparaiso, a city of 270,000 people on the Pacific coast, 110 kilometres northwest of the capital Santiago.
Flames were advancing down the slopes of the city towards its port and Unesco-listed centre driven by strong winds. Many residents watched helpless from distant vantage points as the hills burned bright red. Thick smoke clouded the sky.
Watch: At least 11 dead in Chile fire: police
Firemen, some drafted in from Santiago, were hopelessly outmatched in their battle to stop the blaze spreading.
They were forced to retreat repeatedly as flames reduced homes to cinders, a wall of red towering above them.
The city is spread out over more than 40 hills, hindering emergency vehicle traffic. The vast blaze has caused cuts to power and drinking water in many areas.
The cause of the fire, which began in woodland near the city late on Saturday, was being investigated.
The authorities have set up nearly a dozen shelters to take in those evacuated. Pets were not being allowed in the shelters and animal welfare organisations said some owners were choosing to sleep in the streets with their dogs or cats.
Chile's interior minister, Rodrigo Penailillo, went to Valparaiso and said the disaster decree Bachelet issued on Saturday activated an "exceptional" constitutional process allowing the military to be called in to help.
Valparaiso is one of Chile's most important ports. It lived its era of glory from the mid-19th century to the early 20th century as a stopover point for ships steaming down South America and rounding its southern tip into the Atlantic Ocean.