The opening run of the bulls in Pamplona, Spain, on Sunday left at least five people — including three runners who were gored — hospitalized, officials said.

Authorities said a 46-year-old man from San Francisco, Calif., was gored in the neck in the city's bullring and required surgery. A 23-year-old man from Florence, Ky., was gored in the thigh.

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Additionally, a 40-year-old Spanish man was also gored in the thigh, and two other young Spanish men sustained head injuries during the opening run, which lasted 2 minutes and 41 seconds.

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The running of the bulls — part of the San Fermin Festival in Pamplona, in northern Spain — draws roughly 1 million people to the city each year. During its nine-day run, six bulls and a herd of steer run each morning in the city's narrow streets. The bulls ultimately are killed in afternoon bullfights.

"Runners" race ahead of or next to the bulls while people watch from balconies.

The local Red Cross said emergency personnel attended to 48 people with less serious or minor injuries, including two who were trampled by the racing bulls.

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While bullfights are protected under the Spanish Constitution as part of the country’s cultural heritage, protests by pro-animal rights groups have become a fixture in recent years.

On Thursday — the night before the festival officially kicked off — dozens of semi-naked activists staged a performance simulating speared bulls lying dead on Pamplona’s cobbled streets to draw attention at what they see as animal cruelty for the sake of human entertainment.

The Associated Press contributed to this report.