Terrifying footage shows the moment a seven-storey building collapsed in Kenya - with fears of multiple casualties.

A search-and-rescue mission is underway after a tall apartment building collapsed this morning (Sun) in Kahawa West, Nairobi.

Shocking footage shows the building reduced to rubble with a loud crash, with locals screaming as they flee the scene as plumes of thick dust rise into the sky.

Kenya Red Cross said several families are likely to be trapped inside the collapsed building, according to local reporters.

However, it's unknown how many were inside at the time of the collapse.

Occupants residing in adjacent buildings will also be evacuated as a precaution, it has been reported.

Dicken Muchena, 31, who witnessed the collapse, said: "The building had already been earmarked as a threat to people early today."

"There were signs of collapse so people started vacating."

"I went out to find out more on the ground and that is when the house came down."

"I was shell-shocked to see people who were near the building buried."

"There was horror at the scene and confusion."