Smoldering fires and the risk of collapsing buildings Friday prevented investigators from finding the cause of a blaze that destroyed much of the historic Chiado shopping district.

Civil engineers and other experts were told their inquiry would have to wait until the fire completely subsided in the cellars of the 150- and 200-year-old buildings that were used to store highly combustible materials such as textiles and paper.Firefighters also said the burned-out shells of the Armazens do Gran-dela and the Grandes Armazens do Chiado department stores were probably beyond propping up and could collapse at any minute.

The fire broke out in the Arma-zens do Grandela early Thursday and in the next four hours swept through buildings on the narrow streets of the neighborhood known for its speciality shops and cafes where artists and writers gathered.

One man died and 43 people, six of whom remained hospitalized Friday, were injured.

Fire officials say they don't know what caused the blaze, the worst in the capital in 200 years. News reports raised the possibility of arson.

Union representatives said about 2,000 people, mostly clerical and shop workers, lost their jobs.

Lisbon Shopowners Association President Jose Ferreira de Matos put damages at $600 million, nearly double the estimate of insurance adjustors.