At least 41 people have been killed and 63 others injured in a gun attack in South Sudan’s eastern state of Jonglei, a regional official says.

“Preliminary reports we got indicate that 41 people got killed and 63 got wounded, some of them critically," the official said on Sunday, adding, “Some of the injured are in very bad condition and they will most likely die tonight or later.”

According to Hussein Maar, the acting governor of Jonglei which is South Sudan's largest state, militants led by David Yau Yau are believed to be behind the attack.

Maar said that the attackers were armed with automatic weapons and stole thousands of cattle.

He also noted that some of the wounded people were taken to the country's main hospital in the capital Juba.

In May, in a battle between South Sudan’s military and militants Jonglei, 24 people, including 20 militants and four government troops, were killed and the army recaptured the town of Boma, near the border with Ethiopia, from the militants who had seized the town earlier this month.

In July 2011, South Sudan voted to break away from Sudan following a two-decade civil war that killed about two million people in the East African country. But the new oil-rich nation, which is one of the least-developed countries in the world, has had to confront ethnic tensions and rebellions of its own.

Yau Yau rebelled against the government in Juba after he was defeated in the elections of April 2010. However, he accepted amnesty in June 2011, a month before South Sudan won independence from Sudan after decades of civil war.