At least 11 people have been rescued and taken for medical attention at nearby hospitals by first responders from City Hall and the Kenya Red Cross Society.
Public Works Principal Secretary Gordon Kihalangwa, who was among government officials who visited the scene, said the ill-fated block had 46 residential houses.
It was not immediately clear how many tenants were in their houses when the disaster struck on Friday morning but rescue workers believe more people are still trapped under the rubble.
The owner of the residential flat, only identified as Mama Kanyoni and who was expected to avail tenancy records, was missing from the scene after the building collapsed.
Kihalangwa said search and rescue operations had been greatly hampered by the high number of onlookers who were milling around the scene of the collapsed building.
Emergency and rescue workers also had a rough time reaching the scene due to the poor state of the roads in Tassia estate made worse by the ongoing heavy rains pounding various parts of the city and country.
Underground and surface water also flooded parts of the scene adversely affecting the search efforts in the race against time amid hope of more people still trapped under the rubble being rescued.
"But we can hear a baby crying in there," said one of Red Cross volunteers as emergency and rescue teams stepped up efforts to rescue those still trapped since Friday morning the building caved in.