PAMPLONA, Spain — Charging bulls plowed into piles of fallen thrillseekers Wednesday, goring an American and injuring at least one other person during the annual run through the streets of Pamplona.

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, which makes the sprint safer.

But pile-ups of fallen runners formed at several points, and bulls plowed into at least one of them and ran over others. One man in sneakers, running shorts and a tank-top bumped into the side of bull making a sharp turn and was thrown into the air.

A bull gored 22-year-old Marcus Wolf from Bakersfield, Calif., and left him with a 5-inch (12-cm) gash in his right buttock. He underwent surgery.

"I am not hurt that bad," Wolf said later.

"I was running, and I got caught up with the people. I fell down and the bull climbed up over me. I felt the horn instantly," Wolf said as he recovered in a bed at Navarra Hospital.

"It is my first and final run, but I will definitely come back to Pamplona," he said. "I love it."

The Red Cross said a Greek man suffered a facial injury when run over by bulls.

One bull got separated late in the course, turned back toward the starting point several times and charged at people. At times it just stopped and stared at people looking on from behind a wooden fence.

Herders with sticks tugged on the animal's tail to turn it around and eventually guided it into the bullring where the half-mile (850-meter) run ends.

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 Adrenalin. I'll definitely do it again."

The runs to the city bullring take place at 8 a.m. 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.

Of 18 runners who were hurt in the first two days of this year's festival, six remained in the hospital on Wednesday, the Red Cross said.

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.