A U.N. peacekeeper ​in Lebanon died ‌on Thursday from wounds ​sustained when ​mortar shells hit his ⁠position near ​Marjayoun in southeastern ​Lebanon late the previous night, the ​U.N. peacekeeping ​mission UNIFIL said.

UNIFIL, which ‌did ⁠not say where the shells originated, said ​two ​other ⁠peacekeepers were wounded ​and that ​it ⁠had opened an investigation into ⁠the ​incident.

The force said that an investigation is underway “to ascertain the exact circumstances that led to this tragic incident…The violence must end.”

It is not clear where the shelling originated, but the development comes amid intensifying exchanges of fire between the Israeli military in southern Lebanon and Hezbollah fighters who are not part of Lebanese army.

“Deliberate attacks on peacekeepers are grave violations of international humanitarian law and of Security Council Resolution 1701, and may amount to war crimes,” UNIFIL stressed.

The Serbian authorities have confirmed that the peacekeeper was a Serbian national who had received emergency medical care after his base came under attack. He was then helicoptered to a Beirut hospital where he died.

“We extend our deepest condolences to the family, friends, and colleagues of the peacekeeper who lost his life in the service of peace,” UNIFIL said in a statement. “Our thoughts also go out for the full and speedy recovery of the injured peacekeepers.”

In its announcement UNIFIL highlighted “an increasingly high number of trajectories and impacts” across south Lebanon.