Running with the bulls in Pamplona

Bulls trample revelers on the streets of Pamplona, Spain.  (Jesus Caso / EFE)

A bull stumbles over a fallen runner on the fourth day of the running of the bulls.  (Daniel Ochoa de Olza / Associated Press)

A small convoy of bulls is escorted by a single runner on the streets of Pamplona, Spain.  (A.Arrizurieta / AFP/Getty Images)

Pedestrians hurriedly cede the right-of-way during the running of the bulls in Pamplona, Spain.  (A.Arrizurieta / AFP/Getty Images)

It’s every runner for himself during the fourth bull run of the San Fermin Festival.  (Pedre Armestre / AFP/Getty Images)

Welcomed by cheering crowds, bulls and runners stream into the bull ring in Pamplona, Spain.  (Alvaro Barrientos / Associated Press)

Runners blur into a river of movement in a time-lapse image of the running of the bulls in Pamplona.  (Daniel Ochoa de Olza / Associated Press)

A future bull runner is pursued by a “cabezudo” (or “big head”) as the San Fermin Festival.  (Denis Doyle / Getty Images)

A bull hooks a fallen runner by the shirt on the streets of Pamplona, Spain. Three people were confirmed injured on the second day of the annual ritual.  (Daniel Ochoa de Olza / Associated Press)

The San Fermin Festival, held since 1591, attracts tens of thousands of foreign visitors each year for nine days of revelry, morning bull-runs and afternoon bullfights.  (Daniel Ochoa de Olza / Associated Press)

The bulls used in Pamplona come from the Cebada Gago ranch, which has a reputation for raising fierce animals. They have taken part in the San Fermin festival for 24 straight years.  (Pedro Armestre / AFP / Getty Images)

The running, as seen through a fish-eye lens.  (Pedro Armestre / AFP / Getty Images)