Thousands of daredevil runners charged ahead of six fighting bulls of the annual San Fermin festival, and the three were gored by one that broke free from the pack just before entering the city's bullring, a Navarre regional government statement said.
Aryeh Deutsch, a 38-year-old who has participated in dozens of bull runs at Pamplona, said he tripped and fell amid a crowd of runners as he dashed ahead of the black bull and saw the animal heading toward him as he lay on the ground.
"The next thing I know I am underneath him, I can see his belly and I was trying to roll out of the way to get under the fence and yeah he got me, he got me in the right calf," said Deutsch, an engineer from Cherry Hill, New Jersey.
Deutsch didn't realize at first that he had been gored but got behind the fence when he saw the bull turn around instead of heading toward the ring.
It then charged other runners huddled on the ground near the fence, trying to protect themselves from the beast. That's when the two Britons were gored. After several tense moments, the animal was lured away and into the ring by stick-wielding cowherds.
Deutsch at that point saw he had a hole in his pants from the goring and was bleeding, and was taken on a stretcher to a hospital for treatment. The regional government said one of the Britons, aged 20, was gored in the right leg while the other, aged 29, was gored in the left leg.
None of those gored were seriously injured, and Deutsch was released within hours. Four other people were treated for cuts and bruises sustained in the adrenaline-fueled dash along the 849-meter (928-yard) course. The run lasted just over three minutes.
One person was gored on first day of this year's San Fermin festival, while none were gored on the second day.
The morning runs are the highlight of the annual festival, which became world famous with the publication of Ernest Hemingway's 1926 novel "The Sun Also Rises."
The ornery beasts used in this centuries-old fiesta can weigh 500-plus kilogram (1,100-pounds) and have killed 15 people since record-keeping began in 1924. The most recent killing was in 2009, when a young Spaniard was gored in the neck as he tried to escape a bull by sliding feet-first under a fence separating the course from the crowd watching the run. It was the first death at San Fermin in nearly 15 years.
The runs take place daily until July 14 and are broadcast on state television.
The bulls from the Cebado Gago breeding ranch that ran Monday were herded from a holding pen in the city center to the bullring, where they are normally killed by matadors in afternoon bullfights.
Doctors told Deutsch he received a puncture wound that was 2.54 centimeters (1-inch) deep. The goring was the first that he has received in 53 runs in Pamplona since 2004. And he was planning to run again Tuesday despite the injury.
"I am moving forward," Deutsch said in a telephone interview from Pamplona. "It's a beautiful thing watching that herd run. They are like a thunderstorm on those cobblestones. We like to say we are running with our bull brothers."
Alan Clendenning and Ciaran Giles contributed to this report from Madrid.