In August 2002 a heavy rainfall event lasting more than two days occurred in Saxony/Germany. This led to extreme flash floods and extreme high water levels in some left tributaries of the river Elbe in the Ore mountains (Erzgebirge). Much damage occurred: houses and bridges were destroyed, much sediment moved and a dam broke. About 20 people died. Immediately after the event a mapping exercise of all damages arising from the flood was compiled. The hydrologic and hydraulic processes during the flood were analysed. This analysis included the genesis of the flood, the flood routing, the erosion, plain bed load transport and the sedimentation. The analysis of such an extraordinary event can help us learn how to prevent flood damages in the future.