Ideal firefighting strategies at process plants would include simultaneous suppressing and cooling of all the burning and exposed units, respectively, if firefighting resources are sufficient. As a result, the primary fires can be contained and their escalation into secondary fires via domino effect can be prevented until the fires are fully extinguished. However, when the number of burning units to suppress and exposed units to cool exceeds the firefighting capacity of a process plant, it is not feasible to conduct an ideal firefighting. Consequently, the plant owners need to conduct an optimal firefighting to address the following question: When all the burning and exposed units cannot be considered in firefighting, which ones should be prioritized and included in firefighting so that the risk of fire propagation in the plant can be minimized? For process plants that are close to other land-use developments (residential communities, infrastructures, etc.), conducting an optimal firefighting can become more challenging as it should minimize not only the risk of domino effect within the plant (onsite risk) but also risks posed to the nearby land-use developments (offsite risks). In the present study, considering onsite and offsite risks that may arise from domino effects in process plants, a methodology is developed based on goal programming – a multi-objective optimization technique – for identifying optimal firefighting strategies. Given limited firefighting resources, the developed methodology helps determine which units to suppress and which ones to cool in order to minimize as many risks as possible.