A pungent odour is in the air above the residential area – there is a fire on a nearby factory grounds. A mobile phone peeps: “Warning from the fire department, keep your windows closed as of immediately.” While in the past sirens wailed in such emergencies, a new warning method developed by the Fraunhofer FOKUS institute and public insurance companies exploits the benefits of the Internet and mobile phones. With the KATWARN system, the fire department and emergency response authorities inform citizens about accidents such as large-scale fires, blackouts, and bomb finds via SMS, e-mail, or smartphone app. Registered users find out what needs to be done in their postal code area, enabling them and others to get to safety quickly.