Colombians are preparing to bury scores of decomposing bodies as rescuers continue to search for victims of weekend flooding and landslides that devastated a city in the southern part of the country, killing at least 273 people.

Desperate families queued for blocks in the heat to search a morgue for loved ones who died when several rivers burst their banks in the early hours of Saturday, sending water, mud and debris crashing down streets and into houses as people slept.

Bodies wrapped in white sheets lay on the concrete floor of the morgue in Mocoa on Monday as officials sought to bury them as soon as possible to avoid the spread of disease.

The government has begun vaccination against infection.

"Please speed up delivery of the bodies because they are decomposing," said Yadira Andrea Munoz, a 45-year-old housewife who expected to receive the remains of two relatives who died in the tragedy.

But officials asked for families to be patient.

"We don't want bodies to be delivered wrongly," said Carlos Eduardo Valdes, head of the forensic science institute.

The death toll has ticked up as rescuers searched with dogs and machinery in the mud-choked rubble.

Many families in Mocoa have spent days and nights digging through the debris with their hands despite lack of food, clean water and electricity.

"We spent two days here already. Our family members were identified yesterday and their bodies still haven’t been delivered," Andres Lopez, a survivor, told Al Jazeera.

"There are serious logistical issues. There are only two officials doing the paperwork."

Three days after floodwaters rushed through the city of Mocoa, the authorities said they would check any report of movement that could be a sign of life and are not yet ready to concede that it is too late to find anyone alive from the list of more than 200 people missing.

"We do not like to create false expectations but where there is a possibility of life we will do everything possible," said Carlos Ivan Marquez, director of Colombia's National Unit of Disaster and Risk Management.

President Juan Manuel Santos, who made a third visit to the area on Monday, blamed climate change for the disaster, saying Mocoa had received one third of its usual monthly rain in just one night, causing the rivers to burst their banks.

Others said deforestation in surrounding mountains meant there were few trees to prevent water washing down bare slopes.

More than 500 people were staying in emergency housing and social services had helped 10 lost children to find their parents. As many as 43 children were killed.

Al Jazeera's Alessandro Rampietti, reporting from Mocoa, said the government has declared an economic, social, and ecological emergency in the area to make it easier to transfer public funds for aid and reconstruction.

Families of the dead will receive about $6,400 in aid and the government will cover hospital and funeral costs.

Even in a country where heavy rains, a mountainous landscape and informal construction combined make landslides a common occurrence, the scale of the Mocoa disaster was daunting compared with recent landslides, including one in 2015 that killed nearly 100 people.

Colombia's deadliest landslide, the 1985 Armero disaster, killed more than 20,000 people.