(CNN) –  A rogue militant group formerly allied with al Qaeda kidnapped more than a 150 teenage Kurdish students in Syria and forced them to take Islamic training, a monitoring group and Kurdish officials told CNN on Friday. Radical fighters from the Islamic State of Iraq and Syria (ISIS) are holding the boys ranging in age from 15 to 18 at a Sharia law school in the northern town of Manbij, Nouri Mahmoud, a member of the local Kurdish Democratic Union Party (PYD) in the Syrian city of Kobani, also known as Ayn al-Arab, told CNN. “They are training them in Islam and prayer, but we are afraid that they are teaching them to carry out operations in Kobani. We are very concerned that they will use the children for their terrorism,” Mahmoud said.