The paper explains the factors which made the Ahr flood event of 2021 the deadliest one in Germany, causing more fatalities than all flood events of the previous 40 years together. It points out that 75% of the fatalities occurred outside of the established flood hazard zones. On the basis of individual fatality reports, factors additionally to early warning and evacuation deficits are identified. A particular result is that beyond danger zones like campsites and cellars the percentage of deaths on the ground floor of buildings (37 %) or outside on the street (18 %) were particularly high. Recommendations for improving emergency management of such unprecedented floods are given.