Twelve people were killed and 18 injured in a storm that brought rain, hail and winds of more than 90 kph to Buenos Aires, Argentine authorities said on Thursday.
Residents of the capital and its suburbs woke up to flooding and streets blocked by downed trees and light poles.
The storm also cut electricity to some neighbourhoods and interrupted passenger rail service, while transportation in general was snarled amid heavy Holy Week travel.
One of the 12 fatalities died of electrocution and the rest were crushed beneath collapsing roofs, walls and trees, the emergency management office said.
"Almost a tornado, an infernal thing" was how an official of the Buenos Aires provincial government, Diego Santilli, described the storm that descended on the area Wednesday night.