S America storm kills at least 17
A satellite image shows the storm forming over the region
A violent storm has left at least 17 people dead in northern Argentina and southern Brazil.
Dozens more were injured as rain, hail and winds of over 100km/h (60 mph) destroyed their homes.
At least 10 people were killed and more than 50 hurt in Argentina, according to local officials.
In Brazil, four people died in the town of Guaraciaba, while three people were reported to have died in mudslides heavy rains in the state of Sao Paulo.
The storm also damaged homes in Paraguay.
Several local media reports described the storm as a tornado, but meteorologists called it a severe depression, where tropical warm air and frigid air collide to create instability.
'Incredible' devastation
The worst affected places in Argentina were in the north-eastern province of Misiones, including the small towns of San Pedro, Santa Rosa and Tobuna, where trees and power lines were brought down.
"Whole houses disappeared," said Ricardo Veselka, the civil defence director for San Pedro.
The local mayor, Orlando Wolfart, described the devastation as "incredible".
"This is something we've never seen," he told reporters.
In the southern Brazilian state of Santa Catarina, four people died in the town of Guaraciaba and across dozens of localities reported damage.
Extremely heavy rain caused traffic problems in Sao Paulo and cut off phone services in some neighbourhoods. Three people were reported to have died when landslides caused homes to collapse.
In Paraguay there were reports that 700 rural properties, as well as crops, had been damaged.
The temperature in the capital Asuncion fell from 35C to 12C.
