A house that sunk in Kware area in Embakasi had shown indications it would collapse a week ago, tenants say.
More than four floors were pushed into the ground in the Monday night incident and there are fears that over a dozen tenants are trapped.
Police, National Youth Service personnel and workers from Nairobi City County government are battling remove debris in search of survivors.
“We found workers plastering part of the ground floor,” Mr Elisali said.
“We thought it was a normal repair but yesterday (Monday) a big crack appeared on the stairs. That’s when we realized it was serious.”
After the cracks, he said, someone called the owner who visited the house but he left in a huff.
A few minutes later, police arrived at the scene at 7pm.
The officers ordered the tenants to leave the structure immediately and since it was an emergency, they left without carrying their belongings.
Mr Joas Nemati, who lived on the seventh floor with her wife and child, told the Nation that his wife called him saying they had been ordered to leave immediately.
The occupants assembled at the Downstream Academy grounds where they spent the night in the cold.
However, at around 11pm, some decided to collect their belongings from the building. That is when it sunk, according to witnesses.
“I’m not sure if the police had left the scene and people decided to rescue their things… and I don’t know how many were trapped,” said Mr Elisali.
Every floor of the ill-fated building had 14, one-bedroom houses and the tenants paid 3,500 per month.
Head of security at City Hall Francis Munyambu on Tuesday said most of the people had been evacuated but could rule out others being trapped inside.
Kware MCA Ken Ngondi claimed the building was built using substandard materials.
Mr Mosomo Elisali, a tenant, said they first learned all was not well at the weekend when part of the ground floor plaster started peeling off.
The owner, only identified as George, started repairs on Sunday, he said.
This story was first published on nation website.