Thousands took to the narrow city streets of the northern Spanish city of Pamplona in the annual running of the bulls during the San Fermin festival on Saturday, the Associated Press reported.
It is a Spanish tradition dating back to the 14th century made famous by Ernest Hemingway's 1926 novel "The Sun Also Rises."
Fox News reported six runners, one of them gored in the leg, were taken to nearby hospitals. Officials at the Navarre Hospital Complex said one runner, a 73-year-old man, had been gored in the leg and another five with bruises had been admitted. All were released except the elderly man.
Many of the participants wore traditional white clothing and red kerchiefs around their necks for the occasion.
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Among those who received medical attention were a 21-year-old Japanese person and a 26-year-old Australian national, the AP wrote.
"Running with the bulls was the best experience I've had, so much adrenaline," 27-year-old Mark Martinez, from Los Angeles, California, told CBS News. "I couldn't touch the horns, I might try that tomorrow."
15 people are known to have been killed in the running of the bulls since Spain started keeping record in 1924.