The Peruvian capital awoke Wednesday under an extensive toxic cloud of black smoke billowing out of a burning warehouse full of tires and fuel, raising fears for public health.

Huge fuel explosions ignited by the blaze injured five firefighters and authorities said dozens of people have been treated for respiratory problems at health centers in Lima.

Peru's environment ministry said it could take several days for the smoke to clear.

"The smoke contains carbon dioxide... and elements that are carcinogenic, causing an immediate impact on health, particularly among people with respiratory problems," said Arturo Alfaro, director of the non-governmental group Viva.

The blaze broke out early Tuesday in a four story warehouse owned by Technimotors, which sells motorcycles, tires, motor oil and auto parts.

The four story structure was still burning Wednesday morning as firefighters tried to douse the flames from outside the building.

Fire chief Mario Nunez said the warehouse was "totally filled with tires, oil, and all kinds of flammable material."

"Even though it was full of flammable material there was a welding shop on the top floor," he said.

The intense heat in the interior of the building caused some lateral walls to collapse, and threatened to bring down the rest of the structure, said Nunez.

Residents of Lima's populous La Victoria district were forced to leave their homes because of the heavy pollution.

Angry residents demanded to know how the warehouse was allowed to operate in their neighborhood.

"They've allowed them to have all that toxic material in an area where so many people live," a woman from the neighborhood said on local television.

Huge columns of black smoke from the fire mixed with the fog that normally rises from the Pacific at this time of year, covering the city in a dense, dark cloud.

Blown by sea winds, the cloud settled over densely populated areas in the hills surrounding the city.

Authorities urged residents to cover their faces with masks or dampened handkerchiefs and to wash their eyes.

Lima, which is built on desert dunes, gets very little rainfall and depends on cleansing winds from the sea to clear the atmosphere.