Report: ISIS beat child captives near Kobani Group: 4 say they were among 100 boys taken by ISIS on way back from exams The boys say they and their fellow captives were beaten with hoses and cables ISIS militants forced them to take religious lessons, watch beheading videos ISIS has allegedly kidnapped, raped and killed in its campaign in Syria, Iraq (CNN) -- They'd just finished their middle school exams and were heading home to Kobani, Syria. But rather than relief and celebration, scores of Syrian Kurdish children say they endured torture and humiliation -- at the hands of ISIS. Human Rights Watch, an international advocacy organization, reported the allegations Tuesday based on interviews with four boys who said they were held by the Islamist extremist group for months. While CNN could not independently verify the claims, there certainly is precedent. International authorities, witnesses and people in the middle of yearslong strife in Syria and Iraq have accused ISIS of many misdeeds and war crimes in the past, including enslaving young women and children. Every story is hard to take, and those documented by Human Rights Watch are no exception. Yazidi women sold, raped, enslaved by ISIS The boys, ages 14 to 16, said they were part of a group making the roughly 150-kilometer (100-mile) trek back from Aleppo from exams when ISIS militants halted and detained them on May 29. ISIS let approximately 100 girls go within hours, but they kept the boys at a school in Manbij, some 50 kilometers southwest of Kobani, according to the Human Rights Watch report. Their living conditions there were sparse: sleeping with blankets on the floor, bathing once every two weeks, eating twice a day and getting occasional visits and calls from their parents. And it got much worse from there. The interviewed boys talked about being forced to watch videos of ISIS beheadings and attacks, pray five times daily and memorize parts of the Quran. If they did not do well enough on their religious lessons, if they tried to escape, if they did anything that was construed as misbehaving -- or even if they did not -- the young captives could be beaten with hoses and electrical cables, according to the Human Rights Watch report. The advocacy group said one child was tied up with his hands tied behind his back and one hand tied to his foot after calling out for his mother. "They sometimes beat us for no reason," a 16-year-old boy said. A 15-year-old boy said that the detained children who had relatives in the Kurdish militia known the People's Protection Units, or YPG, were treated the worst. YPG members were seen as nonbelievers in ISIS' extreme brand of Sunni Islam, thus making them second-class citizens at best and mortal enemies at worst. "They (ISIS) told them to give them the addresses of their families, cousins, uncles, saying, 'When we go to Kobani, we will get them and cut them up,'" the boy said. Some of the boys escaped, were released or were swapped for captive ISIS fighters between June and September. The terrorist group released about 75 boys -- including the four interviewed, who have since made their way across the border to Turkey -- in late September, with the equivalent of a U.S. dollar and a DVD featuring religious material. Kurdish officials said, according to HRW, that the remaining 25 boys were released a month later. The children's hometown of Kobani has been the site of a fierce weekslong battle between ISIS and Kurdish fighters. Local Kurds have been aided by U.S.-led airstrikes, as well as the recent arrival from Iraq of Kurdish fighters known as Peshmerga. Iraqi Kurdish fighters join Kobani fight Situated on the Turkish border, Kobani is seen by many as a key battleground in ISIS' fight to expand its already vast territory in Syria. The extremist group has ruthlessly taken over much of this country in the past three-plus years as well as neighboring Iraq, with the U.N. Security Council and others alleging it has "killed, kidnapped, raped, tortured or recruited as child fighters" in the process.