Rescue teams desperately searched for victims around the Poas volcano throughout the early hours of Friday morning and there are fears the death toll could rise.
Search helicopters also flew those in need of medical care to local hospitals, while the US army was due later on Friday to send two Blackhawk helicopters, based in Honduras, to help with the operations, AFP news agency reported.
Hundreds of people remained stranded in the Vara Blanca and Cinchona areas, close to the volcano, officials said.
Around 400 tourists were trapped in a hotel near La Paz waterfalls that was cut off from roads by a landslide.
Authorities said that many residents of the affected area are small farmers who raise livestock or grow strawberries and ornamental plants or rely on increasing tourism.