JUBA, South Sudan (AP) — Two United Nations peacekeepers were killed on Monday when armed men ambushed a patrol traveling to a remote area of South Sudan, according to the United Nations Mission in South Sudan.

Seven others were injured in the attack — three peacekeepers, two members of the South Sudanese police and two civilian staff of the mission, the mission known as UNMISS said in a statement. The two peacekeepers killed were from Ethiopia, U.N. spokesperson Stéphane Dujarric said.

The mission said it had deployed a “Quick Reaction Force” to secure the area and support the emergency response after the attack. The patrol was going to the area of Pajut in the state of Jonglei when it came under attack.

“Such deadly violence targeting UNMISS personnel who are serving to support peace in South Sudan is unacceptable,” Anita Kiki Gbeho, the head of UNMISS, said in the statement.

The killings bring the number of peacekeepers killed by militias since Jan. 1 to nine, Dujarric said.

He stressed that attacks against U.N. peacekeepers may constitute war crimes under international law.

Violence is rampant in South Sudan, where government troops have been combating fighters and militias loyal to opposition leader Riek Machar, who was suspended last year as vice president after he faced charges of treason and other offenses he says are politically motivated. Attacks against peacekeepers are rare.

A 2018 peace deal between President Salva Kiir and Machar, who is under house arrest, has collapsed, leading to fears of a return to full-blown civil war.

More than 450 incidents of violence against humanitarian workers and assets were reported between January and July, more than double the number recorded during the same period last year, according to U.N. figures.

The conflict escalated in December when opposition forces seized government outposts in Jonglei. The government has conducted a counteroffensive since January with aerial bombardments and ground assaults, despite an official commitment to the peace agreement.

The U.S. has urged talks between Kiir and Machar. Earlier this year it called for “urgent action to uphold peace and mitigate the risk of civil war through an immediate return to dialogue among the parties to the 2018 peace agreement.”

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Edith M. Lederer contributed to this report from the United Nations