In October, 2015, South Sudanese government soldiers rounded up a 13-year-old boy along with a group of men grazing their cows near the town of Leer, in Unity State. The boy and the men were then taken to a newly built military garrison and herded into a shipping container. The soldiers slammed shut the container door. The soldiers returned three times, shoving more men into the container, until they numbered at least 53 people. “It was so full, you could not change your position,” the boy told Time Magazine.

As the heat spiked and the air dwindled, the men shouted for water and banged on the metal walls. Soon they began to vomit and collapse on and around the boy. When the soldiers returned the next day and opened the container, everyone was dead. Except for the stunned 13-year-old boy.

Time reporter Aryn Baker and Reportage photographer Lynsey Addario recently spoke to the boy, now in a safe house, about his horrifying experience. Their report offers a troubling portrait of the world’s newest nation, four years after it achieved independence from Sudan and two years after it spiraled into violent conflict between government loyalists and supporters of ousted Vice President Riek Machar. According to U.N. officials, 50,000 lives have been lost in the fighting, and over 2.3 million have fled their homes.

Visit Time.com to read the complete story, with additional video about Aryn Baker and Lynsey Addario’s interview with the boy.

Photo: A 13-year-old boy who survived the killing of over 50 men in a shuttered shipping container. (Photo by Lynsey Addario/Getty Images Reportage)