( CNN ) -- A cargo train derailed and crashed into homes Sunday in a sprawling Kenyan slum , the Red Cross said . Rescue efforts are under way to free residents trapped in damaged homes in the capital city of Nairobi , the agency said . At least five people were transported to a local hospital , Red Cross said on its Twitter page . Kibera -- one of Africa 's largest slums -- is filled with rows of homes made from a mixture of mud , tin , wood and concrete . A railway passes through the neighborhood . The settlement is home to hundreds of thousands . CNN 's Christabelle Fombu contributed to this report .
NEW : At least 20 people are taken to a local hospital . UP : Rescue operations are under way to free the residents . Kibera is one of Kenya 's largest cities . A railway passes through the neighborhood .