Fighting between the South Sudanese army and rebels is forcing U.N. personnel to remain inside a base where more than 20,000 frightened residents are seeking refuge, officials said Wednesday. U.N. personnel are unable to leave the base in Malakal because of the fighting, said Joe Contreras, a spokesman for the U.N. mission in South Sudan. Malakal is the closest city to oilfields in Paloch, about 150 kilometers away. Rebels control some parts of the city and government forces other parts, said South Sudan military spokesman Colonel Philip Aguer.