Residents of a seven-storey apartment building in the Kenyan capital escaped the worst.
Shocking footage showed the apartment block, in Kahawa West, reduced to rubble after it abruptly collapsed .
In a statement Nairobi Governor Johnson Sakaja said the households in the affected building had been issued an evacuation notice last week by the County Planning Department.
The Kenya Red Cross said Sunday that two people have been rescued and taken to Kenyatta University Teaching, Referral & Research Hospital.
Two adjacent buildings have exhibited signs of structural failures, and tenants have been evacuated.
A search and rescue mission are still underway.
Although the edifice had been condemned and tenants ordered to vacate, it is feared some may not have found an alternative place and might have been still inside.
In a statement, the National Construction Authority said the building owner was directed to provide a structural integrity report. But the structure collapsed before this was done.
Media reports suggest the Nairobi County urban planning department is at fault.
Housing is in high demand in Nairobi and unscrupulous developers often bypass regulations, leading to a history of Building collapses in the Kenyan capital.