One thrill-seeker was gored in a leg and four others slightly injured as thousands of adrenaline-fuelled runners raced ahead of six fighting bulls in the streets of the northern Spanish city of Pamplona in the first running of the bulls of this year's San Fermin festival.
Runners, in traditional white clothing and red kerchiefs around their necks, tripped over each other or fell in the mad daredevil annual rush along early morning dew-moistened slippery streets to the city's bull ring.
One youth got the top of his shirt caught on a bull's horn, inches from his face, and was dragged several yards along the ground, but was seen to get up and run away.
The gored runner, meanwhile, was taken to hospital and four others were treated for cuts and bruises, said Red Cross spokesman Jose Aldaba.
The San Fermin running of the bulls festival became world famous with the publication of Ernest Hemingway's 1926 novel The Sun Also Rises. It is also known around the world for its wild all-night street parties which commemorate the city's patron saint.
The massive bulls belonging to the Dolores Aguirre breeding ranch raced from a holding pen on the outskirts of town, where they spent the night before the run, along a 928-yard course to the ring in two minutes, 53 seconds, a relatively slow time.
The last bull in the pack became disorientated and charged into the ring several seconds after the leaders. Once in the bullring it caused panic as it chased several runners around before being coaxed into the safety of stables by cape waving attendants.
"Running with the bulls was the best experience I've had, so much adrenaline," said Mark Martinez, 27, a student from Los Angeles, California, who said he was in Spain on a 10-day holiday.
"I couldn't touch the horns, I might try that tomorrow," he said, clearly oblivious to a basic rule of the centuries-old fiesta that runners should never touch the animals that can weigh some 1,100lbs.
The 8am runs take place daily until July 14 with each charge broadcast on state television. And then, on the afternoon of each day, the same bulls face matadors in the ring.