The deadly floods struck Friday when a year's worth of rain fell in a matter of hours in and around Bahia Blanca, a major port city located in the south of Buenos Aires province, with entire neighborhoods inundated by the fast-rising waters.

The Latin American nation has been particularly shaken by tragic reports of two girls, aged one and five, being swept away in the torrent.

Provincial security minister Javier Alonso confirmed their disappearance Sunday, saying the sisters had climbed onto the roof of a van with their mother to escape the rising waters when a surge ripped them away. Their mother was rescued.

Divers were continuing to search the area, where more than a meter of water remained, Alonso told the Radio Mitre outlet.

Bahia Blanca Mayor Federico Susbielles, meanwhile, told a press conference that the flooding had caused $400 million in infrastructure damage.

Later, in a post on X, he said "there are 16 confirmed deaths, but there are likely to be more" as search efforts continue.

The storm left much of the surrounding coastal area without power. At one point, city officials in Bahia Blanco suspended electricity due to the huge amount of water in the streets.

Argentine President Javier Milei "will declare three days of national mourning" for the deaths, his office said late Sunday, without specifying when the period would begin.

"All areas of the national government will remain dedicated... to assisting the victims in this moment of sorrow for all Argentines," the presidency said in a statement.

The government has authorized emergency reconstruction aid of 10 billion pesos ($9.2 million at the official exchange rate).

Argentine football superstar Lionel Messi offered his condolences on Instagram to the victims' families

"Much strength to all those who are having a rough time in this difficult moment," he wrote.

Environment official Andrea Dufourg said this weekend that the extreme weather event "is a clear example of climate change."

"Unfortunately this will continue to take place... we have no other option than to prepare cities, educate citizens, establish effective early warning systems," said Dufourg, who is director of environmental policy for the city of Ituzaingo outside Buenos Aires.

Bahia Blanca has suffered past weather-related disasters, including a storm in December 2023 that claimed 13 lives. It caused houses to collapse and provoked widespread infrastructure damage.