A plane has crashed in a residential area outside Kenya's capital killing at least six people.

The mid-sized jet, which belonged to an air ambulance service, had taken off from an airport in Nairobi at 2.17pm and was heading to the territory of Somaliland.

The Cessna Citation XLS plane crashed into buildings in the residential area of Mwihoko in Kiambu County just 40 minutes later.

Local police commander Anthony Keter told The Standard newspaper that the accident occurred near Morendat Farm on the northeastern side of Lake Naivasha.

The service provider, AMREF Flying Doctors, did not provide a number of casualties or a probable cause of the crash.