UNITED NATIONS (AP) — A fourth U.N. peacekeeper from Ivory Coast died from injuries inflicted by an improvised explosive device and an attack by unidentified gunmen in northern Mali’s Timbuktu region, the United Nations said Thursday.

In Wednesday’s incident, the U.N. initially reported that three Ivorian peacekeepers died and six were wounded.

“This morning, we have learned from the (U.N.) mission that sadly, a fourth Ivorian peacekeeper has died from his injuries overnight in Bamako,” the capital of Mali, U.N. spokesman Stephane Dujarric said. “Five peacekeepers were injured in the attack; three of them are being evacuated to Dakar for further medical treatment.”

The attack began when the peacekeepers’ vehicle struck an improvised explosive device during a security operation along the Douentza and Timbuktu axis about 20 kilometers (12 miles) north of the town of Bamabara-Maoude in the Timbuktu region, the U.N. peacekeeping mission known as MINUSMA said in a statement. The gunmen who then fired on the peacekeepers later fled the scene and medical evacuations were carried out by helicopters.

The U.N. Security Council on Thursday condemned the attack. It called on Mali’s transitional government to swiftly investigate and bring the perpetrators to justice, while it “reaffirmed that terrorism in all its forms and manifestations constitutes one of the most serious threats to international peace and security.”

U.N. Secretary-General Antonio Guterres strongly condemned the attack on Wednesday and emphasized that attacks on U.N. peacekeepers “may constitute a war crime,” U.N. spokesman Stephane Dujarric said.