Residents, police officers and rescue workers retrieve the body of a victim in Manizales, Colombia, on Saturday.

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NEW: Rescuers are manually removing rubble as rescue dogs search for signs of life

A landslide buries 16 homes in Manizales, Colombia

Red Cross: 18 people were killed, and dozens more are missing

"We cannot lose hope. We are still hoping to find more people alive," a spokesman says

CNN  — 

Rescuers searched for survivors Sunday after a landslide in northwestern Colombia killed at least 18 people and trapped dozens of others, Red Cross officials said.

Workers were manually removing rubble as rescue dogs searched for signs of life, said Cesar Uruena, national relief director for the Colombian Red Cross.

“We have to be very careful, thinking of the people that could be alive,” he said.

Heavy rains caused the landslide, which buried about 16 homes in the city of Manizales early Saturday morning, Red Cross spokesman Leandro Soto said.

CNN affiliate Caracol showed images of buckled rooftops jutting out beneath a massive mound of earth.

“We cannot lose hope. We are still hoping to find more people alive,” Soto said.

Thirteen people have been rescued from the rubble, Soto said, including five whom crews pulled out Saturday night, 15 hours after the landslide.

Sixteen people were being treated for injuries, Uruena said.

About 100 rescuers were working in shifts at the scene, he said.

Psychological support teams were also on hand to counsel victims and their families, Soto said.