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BOGOTA, Colombia — Colombian officials on Friday formally abandoned the search for survivors of floods that killed at least 314 people in the small southern city of Mocoa, though 106 people remain listed as missing.

Emergency workers will turn to excavating roads and buildings, distributing aid and trying to avoid the outbreak of epidemics in the town, where water and power services remained cut a week after the avalanche of debris-filled water poured down from the mountains.

"Without adverse conditions, a person can survive a long time, but with the quantity of mud and rocks in Mocoa, that is very difficult," said Manuel Infante, who has been leading volunteer firefighters who arrived from Cali. "I'd say that the missing are dead," he added.

Defense Minister Luis Carlos Villegas said it "will take a generation" to completely restore the city.

He said the missing could be in hospitals in other cities, lost without phone contact, or simply dead beneath the mud and rubble.

Carlos Ivan Marquez, director general of the national anti-disaster agency, said emergency workers will begin using heavy equipment.