An air ambulance has crashed into a residential area near the Kenyan capital Nairobi, killing at least six people and injuring two others, according to a local official.

Kiambu County Commissioner Henry Wafula said six people on the plane were killed, including doctors, nurses and the pilot - as well as another two people on the ground, while two others were seriously injured. Investigators have been despatched to the scene of the crash to establish its cause.