(CNN) -- Argentina's president declared three days of national mourning Wednesday after heavy rains claimed dozens of lives.
At least 48 people were killed in La Plata, outside Buenos Aires, officials said Wednesday.
"In 12 hours it has rained what it normally rains in the entire month of April," Santiago Martorelli, cabinet chief of the city, told the state-run Telam news agency. The rainfall in that period was 13 inches, he said.
"This storm is a catastrophe without precedent," Martorelli said.
Some 3,000 residents of La Plata have evacuated due to the rain, officials said.
Earlier, eight storm-related deaths were reported in Buenos Aires, the capital.
President Cristina Fernandez de Kirchner toured some of the most heavily damaged areas Wednesday evening.
"I have come to see what happened with this disaster," she said as she entered a flooded home, according to Telam. "I am not going to leave you alone."
Police patrols in the area will increase, she said, due to residents' concerns for their safety.
"People told me that they are afraid," she said, "beyond what they've lost."