Other construction workers who had assembled at the site managed to escape after a loud noise was heard from the centre of the building before it collapsed.
Officially, only two people were killed by falling debris.
The two bodies have been moved to the Kitengela subcounty hospital mortuary.
An audit report by the National Construction Authority (NCA) on building collapses in the country indicates that poor workmanship is the leading cause of building collapses in Kenya.
NCA made the findings following an assessment involving 14,895 buildings.
The assessment found that 10,791 of the buildings were very unsafe and either needed to be demolished or reinforced before occupation.
According to the report, the country has recorded 87 building collapses over the past five years while an estimated 200 people have lost their lives in the last five years and over 1,000 injured as a result.
Notably, 65 percent of collapsed buildings were residential while 25 percent were commercial. Ten percent were mixed-use developments.
According to NCA, 66 percent of the building collapsed after completion while 34 percent collapsed during the construction phase.
The audit report said more than 700 buildings, mostly in informal settlements, are at a high risk of collapsing and require demolition.
