NAIROBI (Reuters) - A United States citizen working in South Sudan as a freelance journalist was among 19 people killed on Saturday during fighting between government troops and  rebels in Yei River state, the rebels and the military said. Christopher Allen, who worked for various news outlets, was killed in heavy fighting in the town of Kaya. South Sudan has been convulsed by conflict since late 2013, pitting President Salva Kiir s troops against those of rebel leader Riek Machar.  On the ground, about 16 (bodies) have been found around the defensive position of the SPLA including this white man,  Santo Domic Chol, a military spokesman, told Reuters. Three government soldiers were also killed, he said. The rebels identified him as Allen, who had been embedded with them for the past week.   We are sad for his family. He came here to tell our story ,  said one rebel who knew Allen. He asked not to be named but said Allen had been in the middle of the fighting and wearing a jacket marked PRESS. Chol said  the rebels had attacked an army base in Kaya but they were repulsed after an hour-long fight. The U.S. government did not respond immediately when Reuters sought comment.  The country spiraled into civil war, with fighting along ethnic lines, after Kiir sacked Machar in late 2013. A peace accord was signed in August 2015 and Machar returned to the capital in April last year to share power with Kiir, before the deal fell apart less than three months later and Machar and his supporters fled the capital. The conflict has forced about 4 million people to flee their homes. Uganda currently hosts more than a million South Sudanese refugees, while over 330,000 have fled to neighboring Ethiopia. 