According to MSF, there are some 40,000 people at the Malakal PoC site. The camp has been providing shelter to people since the eruption of fighting in South Sudan in late 2013, between forces loyal to President Salva Kiir and rival forces aligned with former Vice President Riek Machar.
"As a result of fighting that erupted in the Malakal Protection of Civilian (PoC) site in Malakal, South Sudan, at least 18 people were killed, two of them MSF South Sudanese staff members who were attacked in their homes," MSF said in a Thursday statement.
The fighting occurred inside the camp, run by the United Nations Mission in South Sudan (UNMISS), on Wednesday evening between different ethnic groups and continued on Thursday.
"MSF teams in its hospital received 36 wounded people during the night, one of them an MSF staff member. More casualties are currently arriving," the Thursday MSF statement said, adding that "At least 25 of the initial intake of patients to the hospital had suffered gunshot wounds and eight of them required surgery."
More than a million people have fled their homes in South Sudan amid the violence.
In the latest of many attempted and thus-far unsuccessful peace efforts, Kiir re-appointed Machar as vice president earlier this year in the hope that a united government would end the fighting.