Flash flooding is one of the most dangerous natural disasters you can find yourself in the midst of, because they are generally without warning and they happen, literally, in a flash. Every year there are occurrences and major ones cause death and destruction.
In 2013, 5,000 people in Uttarakhand, India were killed, and in the same year 3,000 Sardinians were left homeless. One of the worst in United States history occurred in 1889 in Johnstown, Pennsylvania, when a dam broke and killed 2,200. Watch this news report about an Israeli flash flood that took the lives of several teens:
While they may occur after the collapse of a dam or levee, they are most often associated with severe water deluges such as major thunderstorms, hurricanes, and meltwater from ice and snowstorms. You can find yourself in the midst of one almost anywhere unless you happen to be at the topmost elevation when one occurs, but they most commonly happen in low-lying areas such as river basins.