JUBA, South Sudan (AP) — An angry mob of South Sudanese youths attacked a U.N. base on Thursday in order to harm members of an ethnic minority sheltering inside. Peacekeepers were forced to open fire, amid rampaging violence that killed at least 12 people, officials there said.

The U.N. mission in South Sudan condemned the “unprovoked attack” and called for a full investigation into the “heinous murders.”