Mudslides killed at least 206 people and injured more than 200 after destroying homes in southern Colombia, officials have said.
They were the latest victims of floods that have struck the Pacific side of South America over recent months, also killing scores of people in Peru and Ecuador.
In the southwestern Colombian town of Mocoa, the surge swept away houses, bridges, vehicles and trees, leaving piles of wrecked timber and brown mud, army images from the area showed.
The mudslides struck late Friday after days of torrential rain in the Amazon basin area town of 40,000.
President Juan Manuel Santos visited Mocoa, the capital of Putumayo department, on Saturday to supervise rescue efforts in the heavily forested region.
He declared a public health and safety emergency to speed up rescue and aid operations. He also expressed his condolences to victims' families.
Putumayo Governor Sorrel Aroca called the development "an unprecedented tragedy" for the area.
There are "hundreds of families we have not yet found and whole neighbourhoods have disappeared", he told W Radio.
The rivers flooded causing a "big avalanche", the army said in a statement.
Some 130 millimeters of rain fell Friday night.
The authorities activated a crisis group, including local officials, military personnel, police and rescuers, to search for missing people and begin removing mountains of debris, Marquez said.
A thousand emergency personnel were helping the rescue effort. Mocoa was left without power or running water; there were reports of some looting in efforts to get water.