(CNN) There are no more people officially missing after mudslides in Colombia killed at least 254, the country's president said Sunday.

Torrential rains Friday night caused three rivers surrounding the southern city of Mocoa to overflow -- sending a torrent of mud and debris surging through the city.

President Juan Manuel Santos said 170 victims had been identified.

He said 43 children were among the dead and 22 more had been hospitalized. A further 203 people were injured, many severely.

"To all [victims], we send our prayers. We send our condolences to their families, condolences from the entire country," Santos said in an address earlier.

Trapped by the river

Photos: Deadly mudslides ravage Colombia Rain battered southwestern Colombia on March 31, leading to deadly mudslides in Putumayo province. The town of Mocoa was severely damaged when as a mudslide tore through it. This April 2, 2017 photo shows the extent of the destruction. Hide Caption 1 of 14 Photos: Deadly mudslides ravage Colombia The day after a mudslide hit Mocoa, people walk among the devastation on April 2. Hide Caption 2 of 14 Photos: Deadly mudslides ravage Colombia A man pauses from digging in the sludge in Mocoa. Hide Caption 3 of 14 Photos: Deadly mudslides ravage Colombia A man and a dog walk down a mud-filled street in Mocoa. Hide Caption 4 of 14 Photos: Deadly mudslides ravage Colombia A fireman searches for victims inside a mud-swamped house. Hide Caption 5 of 14 Photos: Deadly mudslides ravage Colombia A resident stares at the rubble left by the mudslides. Hide Caption 6 of 14 Photos: Deadly mudslides ravage Colombia A man talks on his phone amid the rubble in Mocoa. Hide Caption 7 of 14 Photos: Deadly mudslides ravage Colombia Rescuers search for people among the debris left by mudslides. Hide Caption 8 of 14 Photos: Deadly mudslides ravage Colombia A woman surveys some of the damage in Mocoa. Hide Caption 9 of 14 Photos: Deadly mudslides ravage Colombia Soldiers evacuate one of the injured in Mocoa. Three rivers overflowed and unleashed muddy waves that engulfed homes, cars and bridges. Hide Caption 10 of 14 Photos: Deadly mudslides ravage Colombia Soldiers and civilians search for survivors in Mocoa. Many residents in the area have been reported missing. Hide Caption 11 of 14 Photos: Deadly mudslides ravage Colombia Volunteers and soldiers carry one of the injured in Mocoa. Hide Caption 12 of 14 Photos: Deadly mudslides ravage Colombia People walk through heaps of rubble left by the mudslides in Mocoa. Hide Caption 13 of 14 Photos: Deadly mudslides ravage Colombia An aerial view shows the devastation Saturday, April 1, after heavy rains caused rivers to overflow in Mocoa, Colombia. Hide Caption 14 of 14

Concerned by the increasingly heavy rainstorms Friday, Simon Uribe and his family shifted from their first-floor riverside apartment to the level above.

The river broke its banks 50 meters up the street, splitting and leaving their home effectively surrounded by two strong currents. The electricity cut out.

"At some point, most of the city was (covered) with water. No power but you can see rivers in every street," Uribe told CNN.

"I watched people -- some girls coming down the river -- some bodies coming by the water. It was terrible. It was pretty shocking," he said.

Uribe and his family -- including his 10-month-old son -- escaped to higher ground. The next morning, Uribe found several feet of muddy water where his home had been.

"There was basically no house left," Uribe said. "It was shocking."

Racing against time

A firefighter searches for victims inside a house in Mocoa.

More than 1,000 soldiers and national police officers are involved in the rescue effort, and they are facing enormous challenges.

"The difficulties we are facing are that it is still raining in the region and the (mudslide) turned up a considerable amount of land. There are mobility issues on almost 80% of the roads, and where the road ends, it is three hours to the place where the (mudslide) took place," a police spokesman told reporters.

Photos released by Colombia's military showed rescuers carrying old women and children over downed, mud-caked trees and homes.

A man holds his son as he stands amid the remains of Mocoa.

Santos said Sunday that 10 mobile water tanks were in place and 16 more were on the way to Mocoa, as well as water purification systems. He added that a local hospital was back in operation and medical supplies had been flown in.

He pledged to rehouse those displaced.

"To those who lost their homes, we will build new ones in a safer place. In the meantime, we will give them a monthly rent stipend of 87 dollars. And I have asked the housing minister to begin this initiative today," the President said.

Many people searched through the debris for their possessions after the mudslide destroyed their homes.

Save the Children said at least 70 children had been separated from their parents.

The organization said it would be working to support children and families in the area and was helping to coordinate hygiene kits and temporary friendly spaces for affected children to attend.

"This is obviously a highly shocking and chaotic situation for the population in the most vulnerable situation, especially pregnant women, children and adolescents," executive director Maria Paula Martinez said in a statement calling for support.

What caused the landslides?

Heavy rains, high levels of deforestation, informal housing and dense human populations are some factors that can leave communities vulnerable to landslides, scientists say

CNN meteorologist Michael Guy says it appears that the surrounding region had saturated ground from above-average rainfall this year.

During March and April, the rainy season ramps up with moisture moving in from the Amazon River Valley. Estimates suggest some 127 to 200 mm (5 to 8 inches) of rain fell in the past week.

"Taking into account geography for the region, topography, deforestation due to agriculture, etc ... this creates the perfect environment for mudslides/landslides on the leeward side of the Andes mountains where this town is located," Guy said.

"The floodwaters got stuck up in the mountain and when it came down many people didn't have time to react and they were washed away," a survivor told CNN.

Running for their lives

Aerial footage of the site showed some rooftops poking above the muddy deluge that flattened other homes, bridges and highways.

Power and water supplies to Mocoa have been cut by the disaster, and the hospital system has shut down, firefighters say.

On April 2, rescuers search for victims trapped under debris left by mudslides in Mocoa, Colombia.

Gabriel Umaña, a spokesman for the Colombian Red Cross, told CNN that 300 families had been displaced and more than two dozen homes had been flattened.

Santos personally comforted Marcelo Garreta, who said he could see dead bodies being carried away by floodwaters but was powerless to help.

"We couldn't help anybody, because if we tried we would've been washed away as well. I saw light poles washed away by the floodwaters. This is a great tragedy," Garreta said.