NAIROBI, Kenya — Aid groups in South Sudan say they have treated more than 150 people — mostly for gunshot wounds — during recent battles for the capital of an oil-rich state capital.

Doctors Without Borders said it and the International Red Cross have been treating patients wounded in the city of Malakal.

The group also said Thursday it has been treating patients wounded during fighting among the more than 21,000 people being housed inside the U.N. base there. Doctors Without Borders said displaced residents are reporting the killings and rapes of patients inside the only functional hospital in Malakal.

Violence broke out in South Sudan in mid-December. Despite a cease-fire signed last month, battles continue to rage between government troops and rebel fighters loyal to the country's former vice president.