Several people were injured today at the running of the bulls in Pamplona, including an American who was gored in the abdomen. (See picture gallery.)
On the third day of the San Fermin festival, the six half-ton fighting bulls accompanied by steer stayed in a tight pack for much of the run.
But pile-ups of fallen runners formed at several points, and bulls ploughed into at least one of them and ran over others.
One man in trainers, running shorts and a tank-top bumped into the side of bull making a sharp turn and was thrown into the air.
The Spanish Red Cross said a 22-year-old man from California was gored in the abdomen and will have to undergo surgery. His name was not released.
A Greek man was injured in the face after being run over by bulls, the Red Cross said in a statement.
Earlier, Red Cross spokesman Jose Aldaba had put the injury toll at four. The reason for the discrepancy was not immediately clear.
One bull got separated late in the course, turning back towards the starting point several times and charging at people.
Andy Firestone, an 18-year-old American, called his first run at Pamplona "the most incredible experience of my life. I was afraid, but this is a once-in-a-lifetime thing."
Australian Hugh Fontayn, 19, called it "a rush of Adrenaline. I'll definitely do it again."
The runs to the city bullring take place at 8am daily and are the highlight of a centuries-old festival that became world famous with Ernest Hemingway's 1926 novel The Sun Also Rises.
Professional matadors fight, and invariably kill, the bulls each afternoon of the festival.
Fourteen runners have died in the running of the bulls since record-keeping began in 1924.
The last fatality from a goring was a 22-year-old American, Matthew Tassio, in 1995. In 2003, a 63-year-old Pamplona native, Fermin Etxeberri, was trampled in the head by a bull and died after spending several months in a coma.
On Sunday, a 23-year-old Irishman died after falling from an ancient wall that encircles the old quarter of Pamplona.