Yemeni teenager Nasr Mansour Ghaleb was working at his family's nut shop and hoping to go back to school in his home city of Taez when his life was cut short. The 13-year-old was one of four boys killed by Huthi rebel shelling on a single neighbourhood of Taez on Monday, three years into Yemen's devastating war, according to his family. Nasr was sitting just outside the nut shop when the blast struck. "The shell landed about a metre and a half away from them," Nasr's cousin, Maher Ghaleb al-Khawlani, said. "We rushed to save them and take them to the hospital, but they didn't make it." Taez is largely in the hands of Yemen's Saudi-backed government but has been a key battlefield in the conflict as the rebels hold much of the surrounding countryside. Air strikes by a Saudi-led military coalition on rebel-held areas have also exacted a heavy death toll among children. Children account for at least 1,712 of the more than 8,500 deaths in Yemen since the start of the coalition intervention in March 2015, according to UNICEF. Children are not only at risk of death and disease, but also early marriage in the case of girls and recruitment into militias in the case of boys. "What that means is you have children obviously skipping their education ... but you also have childhoods being stolen," said UNICEF spokeswoman Juliette Touma, who recently visited Yemen. "Across the board, Yemen is not a safe place to be a child," she told AFP. Childhood is especially grim in contested areas like Taez, where Nasr had returned two months before his death, according to his family. His parents had sent him away to school in Sanaa province, where it was safer. They had watched their son suffer a sniper bullet wound and go through surgery early on in the war. Then a missile landed on their home while Nasr and his cousin Rayan were asleep in bed. The house was left uninhabitable, forcing the family into a camp with other displaced residents of the city. But the teenager was intent on starting fourth grade with his old friends in Taez. And so he came home. In July, Nasr took a summer job at his relative's nut shop in Taez. His cousin told AFP it was a family trade: "My brothers, my uncle and I, we all work in Taez. My uncle has a shop selling nuts in Bab Musa while my brother, Abu (father of) Rayan, has a shop selling nuts in Bab El Kabir." Abu Rayan lost his son Rayan when the seven-year-old's school was hit by a mortar last year. - 'He loved to plant trees' - In the same Al-Jamaliya neighbourhood of Taez, on the day of Nasr's death, Issa Yousef was also killed. Issa was just outside their house when a mortar hit, the day before he was due to start high school. "He was 16 years old," his brother Khaled lamented. The family was originally from Al-Jamaliya but had to flee across town twice over the course of the war. They finally fled back to their old neighbourhood, finding refuge in a house that had been abandoned by the family that once lived there. "Our house is completely destroyed and we don't even recognise it anymore," Khaled said. Issa loved soccer, his cousin said. "Before the war he used to wear his sports uniform and go watch his favourite team, the Falcons." "Sometimes he would go watch the Ahli club play at their home stadium, the Martyrs Stadium, in Taez," he said. "He always wanted to hear updates about the Yemeni teams. I don't remember him ever being interested in international clubs." But before the war, Yousef's favourite hobby was gardening. "He had a small garden next to the house that he'd take care of. He would spend his time planting trees, and especially flowers," Khaled said.