The attack, which took place early Thursday morning, was the second in a short period in which around 50 people were killed.
It is unclear who carried out the attack, but an "armed criminal network" active in several states in the northern part of the country is being singled out.
Similar attacks have long been common in the country, and last year, President Salvar Kiir declared a six-month state of emergency after flare-ups of violence.
