Addis Ababa - Nineteen Ethiopian children who were kidnapped last month by South Sudanese gunmen have been released, the Ethiopian government announced on Tuesday, with negotiations underway to free dozens of others.The children, who were among more than a hundred abducted during a cross-border tribal raid on April 15, were freed peacefully following mediation by South Sudanese authorities, the government in Addis Ababa said."There was no fighting," Ethiopian government spokesperson Getachew Reda said."There's been effort on the part of South Sudan to locate the children and work with tribal leaders to free them," he added."We hope the [other] children will be brought back safely and without a need for a fight, but Ethiopian forces will continue to make every effort including taking military action if necessary." The children were brought safely on Monday to the town of Gambella in western Ethiopia, near the border with war-torn South Sudan, the spokesperson said.The Ethiopian army had crossed the border to look for the children after the attack, which left 208 people dead. The gunmen, who were armed with Kalashnikov rifles, also stole more than 2 000 livestock.Murle tribesmenEthiopian officials blame Murle tribesmen for a string of attacks targeting the Nuer, one of the two main ethnic groups in South Sudan, who live on both sides of the border.But this attack was unusually bloody in a region where inter-tribal clashes and livestock thefts are frequent.Dubbed the "Gambella massacre" in the Ethiopian media, the raid reinforced long-standing fears that South Sudan's civil war, which began in December 2013, would spill into Ethiopia.Some 272 000 refugees from the South Sudanese conflict - which has left tens of thousands of people dead - are currently living in the Gambella region.The conflict has split South Sudan roughly along ethnic lines pitting the president's Dinka tribe against the rebel leader's Nuers. Ethiopia believes the raids are not linked to the conflict.Reda declined to say how many soldiers were currently on the South Sudanese side of the border. An AFP reporter saw several military convoys arriving at Gambella airport in the days after the raid.