Hundreds of boys are missing from a Syrian Kurdish prison that held members of the Islamic State [IS] group and their families, after the U.S.-backed Kurdish forces fought IS militants for 10 days to retake the facility, an international human rights group said Friday. The report by Human Rights Watch came a day after IS’s top leader, Abu Ibrahim al-Hashimi al-Qurayshi, was killed in a U.S. raid on his safehouse in northwest Syria. President Joe Biden said al-Qurayshi had been responsible for the Syria prison assault, as well as genocide against the Yazidi people in Iraq in 2014. Residents of …