At least 52 people drowned in their homes and cars, were electrocuted or died in other accidents as flooding from days of torrential rains swamped Argentina's low-lying capital and province of Buenos Aires.
At least 46 people died on Wednesday in and around the city of La Plata, governor Daniel Scioli said. Six deaths were reported a day earlier in the nation's capital.
Many people climbed on to their roofs in the pouring rain after storm sewers backed up. Water surged up through drains in their kitchen and bathroom floors, and then poured in over their windowsills.
"It started to rain really hard in the evening, and began to flood," said Augustina Garcia Orsi, a 25-year-old student. "I panicked. In two seconds, I was up to my knees in water. It came up through the drains - I couldn't do anything."
The rains also flooded the country's largest refinery, causing a fire that took hours to put out. The La Plata refinery suspended operations as a result, and Argentina's YPF oil company said an emergency team was evaluating how to get it restarted.
"Such intense rain in so little time has left many people trapped in their cars, in the streets, in some cases electrocuted. We are giving priority to rescuing people who have been stuck in trees or on the roofs of their homes," Mr Scioli said.
But many complained that they had to rescue themselves and their neighbours as cars flooded to their rooftops and homes filled with up to two metres (6ft) of water.
President Cristina Fernandez arrived by helicopter in Tolosa, a La Plata neighbourhood where she grew up and where her mother was among those evacuated. She announced security measures to combat vandalism, help for identifying the dead, and three days of national mourning for the victims.
She was then surrounded by her mother's neighbours, in a rare uncontrolled encounter with everyday citizens. Some hugged and thanked her. Others complained angrily and shouted at her to "go away". "It's a disgrace," Miguel Garcia, a 58-year-old shopkeeper, said earlier. "They need to govern. My mother-in-law is disabled. We had to carry her up to the roof, and then we had to rescue ourselves because no ambulance would come."
The heaviest rain - almost 16 inches (400 millimetres) in just a few hours, beating historical records for the entire month of April - hit provincial La Plata overnight. A day earlier, the capital of Buenos Aires was hit hardest. About four more inches (100 millimetres more) of rain were expected before the bad weather passes on Thursday, the national weather service said.