A calf, used to entice revelers, jumps into the arena after the running of the bulls at the San Fermin festival, on July 7, 2011, in Pamplona, Spain. The Fiesta de San Fermin, which involves the running of the bulls through the historic heart of Pamplona for eight days, was made famous by Ernest Hemmingway's 1926 novel "The Sun Also Rises." Photographer: Ivan Aguinaga/AP

A calf, used to entice revelers, jumps into the arena after the running of the bulls at the San Fermin festival, on July 7, 2011, in Pamplona, Spain. The Fiesta de San Fermin, which involves the running of the bulls through the historic heart of Pamplona for eight days, was made famous by Ernest Hemmingway's 1926 novel "The Sun Also Rises." Photographer: Ivan Aguinaga/AP

Running of the Bulls

Pamplona
Pamplona

A calf, used to entice revelers, jumps into the arena after the running of the bulls at the San Fermin festival, on July 7, 2011, in Pamplona, Spain. The Fiesta de San Fermin, which involves the running of the bulls through the historic heart of Pamplona for eight days, was made famous by Ernest Hemmingway's 1926 novel "The Sun Also Rises." Photographer: Ivan Aguinaga/AP

Pamplona
Pamplona

A bull goes after revelers during the San Fermin festival. Four runners suffered light injuries. Photographer: Daniel Ochoa de Olza/AP

Pamplona
Pamplona

Runners scatter after a bull broke away from the pact during the second day of the San Fermin running of the bulls. Twelve bulls charged thousands of runners to the city's bull ring, their final destination. Photographer: Denis Doyle/Getty Images

Pamplona
Pamplona

The San Fermin Festival attracts thousands of tourists, who watch the bulls run despite heavy condemnation from animal rights groups. Photographer: Javier Soriano/AFP/Getty Images

Pamplona
Pamplona

Runners and bulls take a corner during the second day of the San Fermin festival. Photographer: Denis Doyle/Getty Images

Pamplona
Pamplona
The seven-day festival honors Saint Fermín, the co-patron of Navarre in northern Spain. During the festival, held in Navarre's capital, runners try to outrun the bulls starting at 8:00 a.m. each day. Photographer: Denis Doyle/Getty Images
Pamplona
Pamplona
Revelers run next to bulls from the Torrestrella ranch at the San Fermin festival, in Pamplona, Spain. Photographer: Ivan Aguinaga/AP
Pamplona
Pamplona
Revelers gather for the 'Chupinazo,' the official opening of the 2011 San Fermin fiestas in Pamplona. The festival of San Fermin, or the Pamplona bull running as it's more commonly known outside of Spain, officially begins every year on July 6. Thousands of people congregate in the square awaiting the mayor's official announcement that the fiestas have begun. Fireworks are launched. Photographer: Daniel Ochoa de Olza/AP
Pamplona
Pamplona
Participants get wet during the 'Chupinazo' to mark the start of the San Fermin Festival at noon in front of the town hall of Pamplona. Tens of thousands of people pack the streets for a drunken kick-off to Spain's best-known fiesta. Photographer: Pedro Armestre/AFP/Getty Images
Pamplona
Pamplona
A reveler jumps from a fountain into the waiting crowd during the 'Chupinazo,' marking the first day of the San Fermin running of the bulls festival. Photographer: Denis Doyle/Getty Images