Juba , South Sudan ( CNN ) -- More than 200 people in South Sudan have been killed in a three-day spree of cattle-rustling attacks that ended Sunday , a state governor said Monday . Kuol Manyang , governor of Jonglei state , said members of the Murle tribe attacked several groups of ethnic Lou Nuer who were in temporary camps where they had brought their herds for grazing . `` The attack has taken place over a wide area in the marshes , the wetlands , '' Manyang said , adding that security forces were unable to deploy to the remote region of Nasir County in the state of Upper Nile , as it is inaccessible by road . Manyang , who is a member of the Dinka tribe , said the Murle crossed from Pibor County , in Jonglei , into neighboring Ethiopia , then traveled north before re-entering South Sudan to carry out the attacks . `` They took the cows and crossed back into Ethiopia , '' he said . `` They are crossing now into South Sudanese territory . '' The U.N. peacekeeping mission said it is investigating the attacks , but could not confirm Manyang 's report of 200 dead and more injured . `` The U.N. peacekeeping mission in South Sudan confirmed reports of attacks on 9 March on a number of Lou Nuer camps on the border areas of South Sudan and Ethiopia , '' said Kouider Zerrouk , a spokesman for the mission . The United Nations said more than 1,000 people were killed last year in Jonglei state , mostly in clashes between the Murle and Lou Nuer . In late December , an estimated 6,000 Lou Nuer marched into Pibor County and killed hundreds of Murle in a series of attacks that lasted into January , according to the United Nations .
Members of the Murle tribe attacked groups of Lou Nuer , the governor of Jonglei state says . The attack took place in a remote area called Ngombe where there are no roads and few people to protect them. In December , Lou Nuer killed hundreds of Murle in a series of attacks .