The European Union (EU) relies on a complex gas transmission network developed to connect production fields, Underground Storage Facilities and Liquefied Natural Gas regasification terminals and supply the demand of a growing number of customers. The EU is nevertheless exposed to gas crises due to different reasons, such as commercial disputes, technical failures of facilities, natural hazards, market failures or attacks. Transmission networks are designed to work under Business As Usual conditions (BAU), i.e. normal conditions, or considering peak demand conditions which networks are being designed to satisfy. When contingencies such as the ones mentioned above take place, flows are typically rerouted to satisfy the demand as much as possible. The ability to estimate consequences of such contingencies in terms of unsatisfied gas demand is always of interest, including which demand nodes will be more affected, and any other strategy implemented in order to mitigate crisis consequences. The present paper address the problem of conducting hydraulic simulations of regional gas networks under peak demand and contingency conditions, implementing mitigation strategies and estimating unserved demand per demand node. The use of hydraulic models avoids simplistic mass-balance models and ensures that the physics of the problem are correctly simulated and restrictions such as the various minimum nodal delivery pressures are accounted for. Application examples are shown for a EU region.