People running ahead of a herd of bulls in an event called El Pilon de Falces, at Falces, in the northern Spanish region of Navarre, on Sunday.
The bull-running route goes along a narrow, downhill path with the mountain on one side and a precipitous drop on the other. It is a nerve-racking experience, but that is also what makes it attractive to participants and viewers alike.
The event takes place here every August, and is one of many that occur in small towns and villages in Spain throughout the year.
During these events, young men in particular are expected to display their courage by running ahead of, and alongside, the bulls.
The event is considered Spain's second most popular running-of the-bulls spectacle after the one in Pamplona, the capital of Navarre province.
However, these events are not without risk. Rampaging bulls have been known to charge at participants and viewers, and sometimes gore them.
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