MOCOA, Colombia -- After an avalanche of mud buried whole neighborhoods in southwest Colombia, residents began the grim ritual of laying the dead to rest.

Mourners close the casket of a victim CBS News

But every ambulance that arrives at Mocoa’s main hospital is a reminder survivors are still being found.

Hope still drives one anguished woman, and another was searching for her nieces’ names on a list posted outside the hospital.

But she didn’t find them. At least 40 of the dead are children.

“It’s very sad what’s happening,” the woman said. “I don’t have words.”

CBS News

Torrential rains pummeled the region on Friday, causing three rivers to overflow. Floodwaters quickly turned into a tidal wave of mud that ripped through the sleeping city in the early hours of Saturday morning. Eight entire neighborhoods were wiped out.

The deluge was well out of the norm; Mocoa received the equivalent of 40 percent of its average monthly rainfall in just one night. Cinderblock and tin-roofed homes in the region were no match for the wall of water.

Hundreds of relief workers poured in, but distributing food was nearly impossible.

The disaster was made worse by deforestation. Trees that normally would have helped absorb the water and hold back the mud have largely been cut for lumber.

Erlinda Enriquez CBS News

Erlinda Enriquez wonders how the town will rebuild.

“I hear from a lot of people that Mocoa has disappeared, that we won’t see more Mocoa. Mocoa has a many good memories,” she said.

Rescue efforts are still underway, but time may be running out as crews pulled another body from the rubble Monday evening.