A local South Sudanese official says over 3,000 people have been killed during tribal clashes that broke out last week in the troubled state of Jonglei.

The commissioner of Jonglei's Pibor county, Joshua Kronyi, says the bodies of 2,182 women and children and 959 men have been counted so far.

Last week, a group of 6,000 armed men from the Lou-Nuer tribe attacked members of the rival Murle ethnic group in the remote town of Pibor. The fighters withdrew when South Sudanese soldiers opened fire.

On Thursday, the U.N. said it was stepping up its peacekeeping presence in Pibor to ensure that the attackers would not return to the village.

The number of casualties has not been confirmed by the South Sudanese Army or U.N. officials. The U.N. peacekeeping chief, Herve Ladsous, said Thursday that peacekeepers in the area have seen “several dozen bodies.”

Many of the tens of thousands of villagers who fled the fighting have returned, but many need medical care, food and water.

South Sudan has declared a humanitarian disaster in Jonglei. It is asking international relief agencies to quickly deliver aid to the state. The World Food Program has been rushing emergency food supplies to the region this week.

South Sudan's government says it will try to arrange reconciliation talks between the tribes. The government is also directing the tribes to return kidnapped women and children to their home communities.

The Lou Nuer tribe blames the Murle ethnic group for attacks on its territory in August. The two groups have fought over cattle and territory for decades. The U.N. says communal violence in Jonglei state killed more than 1,100 people during 2011 and displaced more than 60,000 others.

South Sudan has been plagued with tribal and militia violence since become independent from Sudan in July.