"The conflict has resulted in the death of more than 20 people so far and injuries to more than 50 others," aid group Médecins Sans Frontières South Sudan said.
The camp in Upper Nile State's capital Malakal, which hosts at least 50,000 people, opened when people started arriving there at the start of South Sudan's civil war in 2013.
Tensions started rising last week when women from different groups tussled at a water point in the camp, according to state Information Minister Luke Saadala.
Full-blown clashes erupted after a man was stabbed to death on Thursday, the United Nations Mission in South Sudan (UNMISS), which runs the camp, said.
In December, 166 people, mainly civilians, were killed and more than 20,000 others displaced in the region, according to U.N. High Commissioner for Human Rights.
Fighting at the Malakal camp killed at least 18 people including two MSF staff members, in early 2016.
Calm was returning to the camp on Friday, but UNMISS had reinforced security there, officials said.
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