A rain-sodden hillside collapsed on homes in a suburb of Costa Rica's capital early on Thursday, killing at least 20 people, many as they slept.
At least 14 people are missing.
Dozens of rescuers, some using dogs, searched throughout the day for survivors and the missing. But they found only bodies, including that of a child, said Hector Blanco, a Red Cross spokesman. None of the dead had been identified.
Mr Blanco said Red Cross rescue crews suspended the search on Thursday evening because more rain made conditions dangerous. He said they would begin again on Friday.
President Laura Chinchilla said at least 20 bodies had been pulled out the debris, including four children. She declared Friday and Saturday as days of national mourning because of the tragedy.
The landslide in the suburb of San Antonio de Escazu followed two days of heavy rains that flooded a river near the town and sent 1,500 people to shelters across Costa Rica.
The government declared the country in red alert, the highest level. Ms Chinchilla said the government has 14 million dollars (£8.6 million) available for relief efforts.
The San Antonio area received 6.3 inches (16.1 cms) of rain in just two hours on Wednesday, according to Costa Rica's Meteorological Institute.
Many roads are flooded or blocked by landslides across Costa Rica, and schools nationwide remain closed.
At least 200 homes were underwater in Parrita, a town in the central Pacific region, which received more than 13 inches of rain (33.5 cms) on Wednesday. A bridge leading into the town was destroyed.