Sudan ? In a brazen attack on horseback and from SUVs mounted with anti-aircraft weapons, some 200 gunmen ambushed peacekeepers from a joint U.N.-African Union force in Sudan’s Darfur region, killing seven in fierce battles that lasted more than two hours, U.N. officials said Wednesday.

Twenty-two members of the U.N.-African Union force were wounded in the fighting Tuesday. Attackers outnumbered the peacekeepers by nearly three-to-one.

U.N. Secretary-General Ban Ki-Moon’s office said the joint military and police patrol was investigating the killing of civilians in North Darfur state when it was ambushed by militants driving vehicles armed with anti-tank and anti-aircraft weapons.