A system for mitigating thermal runaway in a battery-powered electric vehicle (EV). The system includes a gas sensor configured to measure a level of at least one type of gas in a vicinity of a battery of the EV, a thermal event detector configured to determine, based on the measured level of the at least one type of gas, that the battery is experiencing out-gassing, and a communications interface configured to transmit an alert to a fleet management system regarding the out-gassing of the battery. The fleet management system alters an assignment of the EV in response to the out-gassing of the battery.