Hundreds of armed attackers from a South Sudanese tribe that suffered a devastating assault last month charged into three villages, burned them to the ground and killed 57 people, an official said Friday, an act that perpetuates a cycle of revenge attacks in the world’s newest nation.

Some 400 men from the Murle ethnic group attacked the Lou Nuer villages on Wednesday, said Simon Hoth, a county commissioner in Jonglei state, the site of devastating violence the last three weeks. Hoth, a member of the Lou Nuer, said 57 were killed and 40 people were missing and likely abducted.

Twenty-five women and 23 children were among those killed in the Uror county attack, Hoth said. Fifty-two people were wounded.

“They have butchered these people,” he said. There was no immediate independent confirmation of Hoth’s figures.

Murle fighters were accused of killing 22 people in similar attacks in neighboring Akobo county on Sunday.

Uror was the scene of a larger Murle attack in August in which an estimated 600 Lou Nuer were killed. Those attacks prompted a series of retaliatory raids by the Lou Nuer in Pibor county beginning Dec. 23. One Murle official has said that 3,000 Murle died in those attacks. Neither the central government or the U.N. has confirmed that figure, but scores are feared to have died.

The government of South Sudan recently declared Jonglei state a disaster area. The U.N. mission in South Sudan estimates at least 60,000 people have been affected by the ongoing violence. The UN operation says it has launched one of the most “complex and expensive” humanitarian operations since the end of the Sudanese civil war in 2005.

South Sudan became the world’s newest country last year after decades of war with Sudan, but it is now experiencing massive internal violence.

But with retaliation attacks occurring more and more frequently, there is little hope for an end to these clashes. Cattle raiding is at the heart of the tribal clashes. The Lou Nuer are said to have stolen tens of thousands of cattle from the Murle in the December attack.

“Arms are still in the hands of the civilian population,” said Jonglei Gov. Kual Manyang Juuk. “And these attacks will continue, definitely.”

Juuk said the government is sending police to patrol the area, but Jonglei’s extreme underdevelopment makes securing the area difficult. “This is a challenge for the government. They don’t live in formal towns,” he said.

Hoth said Uror’s residents have little hope of being kept safe. “People are now living in fear because the whole county has no security. The U.N. is not there and the (South Sudan military) is not there.”

The area is also desperately short of health care to treat those hurt in the fighting.

Heather Whelan, a spokeswoman for humanitarian group Doctors Without Borders, said the group airlifted 12 seriously wounded patients from its clinic in Yuai to receive surgical treatment in neighboring Upper Nile state. Whelan said five of the victims were women and “six were children under 5, with beating or gunshot wounds.”

The International Organization for Migration said Friday that an IOM convoy of four trucks carrying kits that include kitchen utensils, soap, jerry cans, blankets, plastic sheeting and mosquito nets is en route to Pibor town in Jonglei. The convoy – the first by road since the recent violence began – will be delivered to about 7,500 people.

Associated Press