Unidentified assailants killed two United Nations peacekeepers and injured two others in southeast Central African Republic (CAR), the U.N. mission in the nation said Wednesday. An attack on peacekeepers could constitute a war crime.

“No claim can justify that individuals direct their grievances against peacekeepers whose presence [here] has no other objective than to help the country to end this cycle of violence,” Parfait Onanga-Anyanga, the special representative of the secretary-general in the country, said in a statement.

Onanga-Anyanga, also the head of the U.N. Multidimensional Integrated Stabilization Mission in CAR, which is known by its French acronym MINUSCA, said authorities will make “every effort” to bring the attackers to justice.

The U.N. convoy was on its way to Obo city carrying fuel from Zemio when it was attacked by unknown assailants who killed two Moroccan peacekeepers and then escaped, MINUSCA said in the statement. MINUSCA’s spokesman Vladimir Monteiro added that the two injured peacekeepers were receiving treatment and one of them was severely wounded.

The landlocked nation in Central Africa descended into conflict in 2013 when the primarily Muslim Séléka rebels took control of the mainly Christian country throwing then-President François Bozizé out of office. This sparked a backlash from Christian militia. The ensuing clashes have left thousands displaced.

Séléka, in 2014, relinquished power over to a transitional government following international pressure. However, despite the presence of MINUSCA, a French mission and successful elections, violence continued. France withdrew its mission in October but nearly 350 French soldiers remained to help with the U.N. mission. 

MINUSCA has been accused of inaction in CAR with civilians holding anti-U.N. protests. An outbreak of violence in September 2016 led to the deaths of over 75 people including civilians. The U.N. mission in the country lacks proper training and “the resources it needs to adequately protect civilians,” rights group Amnesty International said of the September violence.

Meanwhile, local government officials have accused U.N. peacekeepers of working with armed militia.

“Their collusion with armed groups has gone too long,” CAR’s Interior Minister Jean-Serge Bokassa reportedly said.

A U.N. inquiry also named 41 peacekeepers allegedly involved in sexual abuse and exploitation in the nation between 2014 and 2015. The report claimed that the peacekeepers had abused women and even minors in exchange for food or clothing. The international organization has, however, taken little action against individual soldiers.