Torrential rains killed at least 10 people in Sao Paulo overnight, adding to a wet-season death toll in Brazil's southeast suffered mainly by residents of vulnerable slums, emergency officials said Tuesday.
The toll, revised downward from an earlier estimate of 13 dead, was given by the state's fire service, which said three people were missing in the disaster.
Mudslides in shantytowns in the north of the city accounted for most of the deaths.
In one case, a mother and her daughter perished when their home was hit. In another, a homeless man was drowned when a strong current carried him away while he was on a busy road.
The situation in Sao Paulo early Tuesday was "chaotic," said television network Globo.
It showed images of flooding from rivers that had broken their banks and cut several highways and principal roads, causing massive traffic jams in some areas for a few hours.
Motorists were seen abandoning semi-submerged cars and wading in waist-high water. Passengers in a bus waved at a helicopter.
In one northern slum where two people died, television showed a mudslide that carried away the face of a hill, knocking trees over and slamming into a flimsy home.
The southern hemisphere summer usually causes daily rains in Sao Paulo as humidity builds up. Flooding and deaths are common during the season.
But a cold front that arrived late Monday made the rains heavier and more prolonged, causing the overnight death and destruction.
The 10 dead listed by Sao Paulo's fire service added to six rain-related fatalities recorded last week, and more than 20 deaths in the entire southeast Brazil region since the wet season started in November.
In all, nearly 40 people have died, according to a tally of official tolls which includes five in the state of Espirito Santo and 16 in neighboring Minas Gerais.
More than 30,000 people have been forced to abandon their homes and find refuge with relatives or in state-run shelters.
The CEAGESP, an entity that runs Sao Paulo's huge warehouse system, said it was forced to close one of its depots for several hours after a nearby river overflowed.
Sao Paulo's Emergency Management Center said 125 areas had been flooded in the city.
It also said the amount of rain that fell on Sao Paulo overnight was as much as it normally receives in more than a week.
The rainfall recorded so far this month accounted for nearly the total average precipitation for all of January.
The center's meteorologists said the cold front had headed north, towards Rio de Janeiro, but the weather over Sao Paulo remained unstable, with more rain forecast during the day, albeit lighter than before.
"The risk of flooding and landslides remains high, given that the ground is saturated," it warned.
According to the daily Estado de Sao Paulo, a total of 473 people died across Brazil in rains and flooding in all of 2010, and 7.8 million people were affected.