The United Nations is reporting another deadly attack in the disputed region of Abyei area that's claimed by both Sudan and South Sudan.

It's the fourth fatal attack in two months in the oil-rich area, signally a deterioration of security.

According to U.N. spokesman Stephane Dujarric, the U.N. force there reported that some 100 armed Misseriya nomads allied with Sudan attacked the village of Marialachak on Monday. The attackers killed four members of the majority Ngok Dinka, wounding three others and abducting four boys and four girls.

Dujarric said the U.N. launched patrols to engage the attackers and that the operation is still going on. In a firefight near the village of Shegag, he said three Misseriya were killed and four captured.