This study describes the efforts of the Mexican Red Cross institution located in the metropolitan area of Monterrey, México to reduce ambulance response time. The major focus for improving the performance of emergency medical systems has been the reduction of ambulance response time by determining the optimal number and locations through the use of mathematical modeling.  A general two-stage scheme consisting of a geospatial - time statistical analysis and a mathematical modelling stage is applied based on an emergency call database generated from during 2016 and the beginning of 2017. The mathematical modelling stage includes the application of models with various optimization criteria. Scenario analysis for the resulting demand levels per day and various combinations of fixed and mobile ambulance bases are evaluated. Results of a pilot program are provided.