The United Nations said several people were wounded in South Sudan on Thursday after gunmen attacked civilians sheltering inside a U.N. peacekeeping base in the town of Bor. The top U.N. aid official in South Sudan, Toby Lanzer, said he was "outraged" by what he said was an "attack of armed youth in Bor on civilians seeking protection." Nearly 5,000 civilians are sheltering inside the fortified base of the U.N. Mission in South Sudan (UNMISS) in the town, one of the most bitterly contested regions in the four-month-old conflict in the world's newest country. The civilians fled into the base weeks ago amid brutal ethnic massacres.