Four people were killed and shops owned by immigrants in South African townships in the coastal city of Durban looted and burnt, police said on Monday, as violence between residents and foreign nationals escalated. Those killed include an Ethiopian, whose shop was petrol bombed last week and two South Africans. Hundreds of people fled their homes after the violence broke out two weeks ago, while police said 28 people have been arrested for looting and torching immigrants' shops. South Africa, with a population of about 50 million, is home to an estimated 5 million immigrants.