What explains China’s mass atrocities against Uyghur and other Muslim minorities? Repression and discrimination had been common practice for decades but had never before risen to the level of mass atrocity. From a security standpoint, the indiscriminate atrocities seem unnecessary. There was no meaningful Uyghur insurgency and the Chinese government already had a far-reaching surveillance system in place that made selective violence a feasible alternative to indiscriminate atrocities. Why did China target the Uyghur when it did? Building on research on elite rivalry and mass violence, we suggest new mechanisms for how seemingly irrational atrocities can provide private security benefits to authoritarian elites. We argue that anti-Muslim atrocities are part of Xi Jinping’s consolidation of power. We posit that Xi utilized mass atrocities to build a new security apparatus independent of traditional government command structures. In part, indiscriminate violence is used to reorganize parts of the security apparatus, such as the People's Armed Police. In part, the violence generates new security structures, which are manned by Uyghurs and Muslims willing to repress their own social group. They, therefore, do not suffer from divided loyalties of (Han) Chinese troops and could, therefore, also be deployed against challenges from rival elites or against popular uprisings in other areas of China. By accounting for the private security benefits that atrocities provide to authoritarian elites, we suggest new explanations for violence that has been hard to explain. The consideration of personalization and private security benefits could therefore help explain both the nature of atrocities against outgroups as well as their timing.