At least 10 people have been killed by catastrophic floods in northern regions of Chile after thunderstorms brought the equivalent of 7 years of rain in just 12 hours on March 26. Search and rescue operations are still in progress and authorities fear the number of casualties will rise. Flooding has affected the regions of Atacama, Antofagasta and Coquimbo, all located in the Atacama Desert, one of the driest regions of the world.

Heavy rainfall and consequent river overflow, flash floods and landslides knocked out power and communication lines, destroyed infrastructure and made roadways impassable.

A state of emergency is in effect since March 26 for the Atacama Region and the Antofagasta municipality. The Health Ministry has declared a Sanitary Alert in Copiapó, Tierra Amarilla, Diego de Almagro and Alto del Carmen.

Chile’s Deputy Interior Minister Mahmud Aleuy called the flooding “the worst rain disaster to fall on the north in 80 years.”

The Atacama Desert is an extremely arid region and has been for millions of years, Weather.com senior meteorologist Nick Wiltgen explains. “As a result, the terrain is hard and rocky because rainfall isn’t frequent or abundant enough for either weathering rocks into sand or supporting the kind of ecosystem that would help turn rocks and minerals into soil. Without soil and plant cover to help absorb rainfall, it just runs off instantly as torrents of water.”

Between Thursday and Friday about 24 mm fell on the city of Antofagasta, an area that typically receives about 1.7 mm of rain in a year, according to the Chilean meteorological service.

Southern Peru was also affected by recent heavy rain. Intense rainfall in Chosica caused deadly mudslide on March 23 which left 8 fatalities, 6 missing and 25 people injured. In addition, 153 houses have collapsed as a result of this event.