JUBA, South Sudan (AP) — The United Nations says one of its peacekeepers was killed in South Sudan when a U.N. convoy was attacked.

The U.N.'s chief of peacekeeping in South Sudan, David Shearer said that Lt Commander Ashraf Siddiqui from Bangladesh was part of a convoy protecting humanitarian workers traveling from Yei to Lasu in Central Equatoria province. Shots were fired by a group of unknown gunmen and Siddiqui died from his injuries shortly after, said the U.N.

The U.N. said it is concerned because this is the third attack on peacekeepers in a month.The two other attacks occurred in Unity State.

South Sudan's five-year civil war has killed tens of thousands and displaced millions.