In the case of big events where hundreds or even thousands of people may gather together, task forces of police units, fire brigade units, medical corps units and so on are usually sent to the happening in order to ensure safety and help within short response time. Defining the number of required task force units and locating these task force units within the event area is a critical problem for the commanding decision maker. In this paper, we will first reveal how such decisions are usually made in practice today by reporting the result of interviews with practitioners who were in charge in such situations in Germany. Then we will provide mathematical models and report on computational studies to demonstrate how these decisions can be supported by operations research techniques. Finally, using data from a practical case in the city of Dresden where 50,000 people gathered together, we show that our models can indeed be used to solve real-world problems using commercial software.