VALPARAïSO, Chile - At least eleven people have died in a huge fire in Chile’s port city of Valparaiso famous for its UNESCO-listed historic center, officials said Sunday.

The blaze, which started in woodland near the city on Saturday and whose cause is under investigation, destroyed 500 homes and forced the evacuation of more than 5,000.

“So far, there are at least 11 fatalities from the fire,” police official Colonel Fernando Bywaters told Radio Cooperativa.

The latest death toll came as President Michelle Bachelet arrived in the hard-hit city, 120 kilometers (75 miles) west of the capital Santiago, to coordinate the emergency response after declaring it a disaster zone. “This is the worst catastrophe Valparaiso has ever seen,” the regional administrator, Ricardo Bravo, told reporters.

The military has taken over security in the popular tourist hub, located on the Pacific coast with a population of 270,000.

At dawn, pockets of fire were still active and firefighters warned that extinguishing them was complicated by the area’s hilly geography, narrow streets and persistent strong winds.

Overnight, many residents watched helpless, from distant vantage points, as the hills burned bright red. Thick smoke clouded the sky.

Hundreds of firemen were hopelessly outmatched in their battle to limit the blaze. They were forced to retreat time and again as flames reduced homes to cinders, a wall of red towering above them.

Early in the morning, massive tongues of flames advanced down the slopes of the city towards its port and heritage-listed center, driven by strong winds.

More than 200 inmates at a women’s prison were evacuated due to “large amounts of smoke produced by the fire,” said Tulio Arce, regional prison guard director.

With the city spread out over more than 40 hills, emergency vehicles had trouble getting to their destinations.

“My brother’s house was entirely burnt. We had only finished it two weeks ago. We tried to save something but it was truly an inferno,” one resident, Cristobal Perez, told the Chilevision television network.

“I started to become overcome by the smoke along with my two dogs. It was terrible - impossible to breathe,” another resident told the channel.

The vast blaze has caused cuts to power and drinking water in many areas.

Chile’s interior minister said the disaster decree issued by Bachelet Saturday had activated an “exceptional” constitutional provision allowing the military to be called in to help.

The navy, which has a major base in the port city, immediately responded by taking over security. It deployed uniformed personnel into the streets to maintain order and to help with the evacuations.

Valparaiso is one of Chile’s most important ports. It lived its era of glory from the mid-19th century to the early 20th as a stopover point for ships steaming down South America and to round its southern tip into the Atlantic Ocean.

The center of the city still features the many colored houses dating from that period, built by European immigrants. Its cobbled streets and funicular trams running up near-vertical rails supported its 2003 listing as a UNESCO-protected heritage site.

Fires occur frequently in central Chile, where summer sends temperatures soaring. In February 2013, some 105 homes were destroyed in Valparaiso, affecting 1,200 people, after a 27-year-old man started a blaze.