Two survivors have been found alive two days after a six-storey building collapsed in the Kenyan capital, Nairobi

Authorities said the building collapse on Friday killed at least five people, injured 31 others and left 24 more missing. When the two survivors were found Sunday morning, a crowd of onlookers burst into cheers and claps.

Nairobi Police Chief Philip Ndolo said the rescue of a man and a woman had invigorated emergency workers with hopes of finding other survivors. He said the two were in stable condition in a hospital.

"Given we have rescued two people two days after the incident, we hope to find more survivors. Remember there is more than 20 people missing," he said.

Ndolo said the heavy rains that Kenya was experiencing, more than 300 percent above normal, were slowing the rescue operation.

It was not immediately clear what caused the building, which the Red Cross said housed 22 families, to collapse.

A military member at the scene told The Associated Press News Agency they had been communicating with people believed to have been trapped in pockets of debris. He said some were screaming for help but the sounds had died down as time wore on. He insisted on anonymity because he is not authorised to speak with the media.

Building collapses are common in Nairobi, where housing is in high demand and unscrupulous developers often bypass regulations.

On Saturday, one person died and others were injured when the balcony of single-story building in Chuka in central Kenya collapsed.

In September, a school collapsed in Nairobi, killing at least seven primary school children.

After eight buildings collapsed and killed 15 people in Kenya in 2015, President Uhuru Kenyatta ordered an audit of all the country's buildings to see if they were up to code.

The National Construction Authority found that 58 percent of the buildings in Nairobi were unfit for habitation.