Live streaming of immersive multimedia content, e.g., 360-degree videos, is getting popular due to the recent availability of commercial devices that support interacting with such content such as smartphones/tablets and head-mounted displays. Streaming live content to mobile users using individual connections (i.e., unicast) consumes substantial network resources and does not scale to large number of users. Multicast, on the other hand, offers a scalable solution but it introduces multiple challenges, including handling user interactivity, ensuring smooth quality, conserving the energy of mobile receivers, and achieving fairness among users. We propose a new solution for the problem of live multicast streaming of 360-degree videos to mobile users, which addresses the aforementioned challenges. The proposed solution, referred to as VRCast, is designed for cellular networks that support multicast, such as LTE. We show through trace-driven simulations that VRCast outperforms the closest algorithms in the literature by wide margins across several performance metrics. For example, compared to the state-of-the-art, VRCast improves the viewport quality by up to 2.5 dB. We have implemented VRCast in an LTE testbed to show its practicality. Our experimental results show that VRCast ensures smooth video quality and saves energy for mobile devices.