AP

Revelers hold up traditional red neckties during the 'Chupinazo' the official opening of the 2007 San Fermin fiestas in Pamplona, northern Spain.

PAMPLONA, Spain - Thousands of revelers sprayed each other with sparkling wine and the mayor of this northeastern city launched a skyrocket at noon Friday to start Spain's most famous festival, the San Fermin running of the bulls.

"Men and women of Pamplona, viva San Fermin!" Mayor Yolanda Barcina shouted from the city hall balcony. Crowds packed the town hall square, most dressed in the traditional garb of white shirts and trousers, and red handkerchiefs.

Residents threw water on the revelers from balconies to cool them off.

The launch of the skyrocket, known as the "chupinazo," began the nine-day fiesta that was popularized internationally by Ernest Hemingway's 1926 novel "The Sun Also Rises" and centers around the daily running of the bulls.

The first bull run takes place Saturday. The spectacle, repeated each day until July 14, is broadcast live on Spanish television.

The festival, held since 1591, attracts tens of thousands of people. Many had spent the night drinking and partying.

Sara Newey, 23, and Rene Armstrong, 25, from Perth, Australia, recounted everything they had to drink in the last 12 hours: a bottle of Jack Daniels, several bottles of sangria and six beers each.

"You just have to keep going," Newey said, holding a carton of sangria in one hand and a bottle of sparkling wine in the other. They came on a tour with 600 other Australians.

Thuy Trinh, 28, a nondrinker from London, might have been the only sober person among the throngs.

"It's a bit crazy, but I love seeing people enjoying themselves," she said.

In the runs, held at 8 a.m. daily, people test their mettle and stamina by racing with six bulls along a 875-yard route from a corral to the city bullring. The bulls are fought by professional bullfighters each afternoon.

Since records began in 1924, 13 people have been killed in the runs. The last fatality occurred in 1995, when a 22-year-old American was gored to death.

On Thursday, hundreds of members of the U.S.-based People for the Ethical Treatment of Animals, staged a near-naked protest march, shouting slogans such as "Torture isn't culture," and "Bulls yes! Bullfighters no!"