Thousands of thrill-seekers from around the world are gathered in northern Spain for the annual nine-day festival featuring the San Fermin running of the bulls.

Crowds gathered in the town hall square in Pamplona Monday.  Many of the revelers were dressed in the traditional white shirts and red handkerchiefs as they awaited the launch of the "chupinazo" skyrocket that officially opens the festival.

The first bull run is set for Tuesday, when six bulls will be run from their corral through the cobblestone streets of the old town.  The spectacle will be repeated every day until July 14 and will be replayed on television across much of the world.

The centuries-old festival was popularized internationally more than 80 years ago by American author and Nobel Laureate Ernest Hemingway, in his novel "The Sun Also Rises."

Last year's festival also featured protests by hundreds of animal rights activists who stripped to their underwear and marched through the streets to protest what they consider to be the cruel treatment of animals.

At least 14 people have been killed and hundreds more seriously injured over the past century, trying to avoid the bulls rampaging through the narrow streets of the town.

Some information for this report was provided by AFP and AP.