The bull that led the pack thrust its horn into Hillmann's buttocks before flipping him onto the street.
"I flew up in the air and landed on my back. I didn't know I was gored at first", he told the AP.
Many people are injured, and even killed, during the running. "I pulled down my pants and there was blood".
"I am probably going to run tomorrow or the next day, sure at this festival", he said. "The first time, I wasn't walking for a week".
The 39-year-old Irishman hurt during yesterday's run suffered light trauma injuries to his chest. While their identities have not been revealed, the men were aged 29 and 35.
Three other Americans, two Frenchmen and three Spaniards - all men - needed treatment at the hospital for injures received during the frantic and crowded run of thrill-seekers.
Hillmann was in Pamplona for a 12th consecutive year to brave the bulls and ran on Friday.
2 Americans Spaniard gored during 'Running of the Bulls.' 7 DEL 7 VIA APTN AP
The Red Cross said they treated 77 people for assorted minor injuries after the race.
Tens of thousands attend the nine-day fiesta, which was popularised internationally by Ernest Hemingway's 1926 novel 'The Sun Also Rises'.
"It changed my life".
Whether the movement will break into the legal realm remains to be seen.
Matadors used capes to usher the runaway bull into a pen under the bullring, sparing onlookers serious injury. People think this is just crazy people running.
Herders had to bring out the bull - called Diputado, which means MP in English - using steers, but it soon raced in front of the animals guiding it along the course.
Live TV captured the moment when a competitor was trampled by the animals racing through the streets of Pamplona. I usually get premonitions.
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