🚨#BREAKING: Hazmat crews are on the scene, as a mass casualty incident has been declared due to a chemical spill 📌#MissionValley | #California Numerous emergency services, including Hazmat and other agencies, are currently on the scene in Mission Valley, California, where a mass casualty incident has been declared due to a chemical spill. Officials report that approximately 10 pediatric patients and 2 adult patients have been exposed to a chlorine release and being treated.