254 dead in Colombia mudslides, including 43 children

Santos, who traveled to the southern town to personally oversee relief operations, warned the toll could keep climbing.

"Unfortunately, these are still preliminary figures," he wrote on Twitter.

"We offer our prayers for all of them. We send our condolences and the entire country's sympathies to their families."

Survivors described gruesome scenes in the remote southern town, as rescuers kept up a bleak search for victims in the muck and debris.

Covered in mud, 38-year-old Marta Gomez told of going to search for her missing niece - and making a chilling find instead.

"I went to look for my niece, but I couldn't find her. I dug and dug and found what turned out to be a baby's hand. It was horrible," she said in a shelter set up for the newly homeless.

As she stood in line waiting to register for government assistance for those who lost their houses, she told AFP she had given up on finding her niece.

"The mud took her away. I'll never see her again," she said, clinging to the leash of her equally muddy German shepherd.

Rescuers worked in stifling heat under a cloudy sky in the remote Amazon town, the capital of Putumayo department.

The debris left by the mudslides was everywhere: buried cars, uprooted trees, children's toys and stray shoes sticking up out of the mud.

The torrent of mud, boulders and debris struck the town with little warning late Friday after days of heavy rains that caused three area rivers to flood.

It swept away homes, bridges, vehicles and trees, leaving piles of wrecked timber.

Most of the hardest-hit neighborhoods in the town of 40,000 are poor and populated with people uprooted during Colombia's five-decade-long civil war.

A "profoundly saddened" Pope Francis said he was praying for the victims.

Santos declared an emergency to speed up aid operations.

Health authorities said they had dispatched sanitation specialists in hopes of preventing outbreaks of disease.

An unexpected offer of help also came from the Revolutionary Armed Forces of Colombia (FARC), a leftist rebel group engaged in a historic peace process with the government.

It said FARC members were prepared to help rebuild the town.

Marta Ceballos, a 44-year-old street vendor, said she lost everything, but is thankful her family is alive.