At least 20 people died and more than 100 were left homeless Wednesday by torrential rains that fell during the night in Sao Paulo, wreaking havoc in Brazil's largest city.

The record rainstorm, accompanied by high winds and lightning, flooded streets, interrupted electric power, telephone service and residential natural gas supplies in large parts of the city of 16 million people, authorities said.The bad weather, which started Tuesday, led authorities in adjacent industrial cities to declare a "state of public calamity."