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Revelers are sprayed with wine during the launch of the 'Chupinazo' rocket, to celebrate the official opening of the 2014 San Fermin fiestas, in Pamplona, Spain, Sunday, July 6, 2014. Revelers from around the world kick off the festival with a messy party in the Pamplona town square, one day before the first of eight days of the running of the bulls glorified by Ernest Hemingway's 1926 novel "The Sun Also Rises." (AP Photo/Daniel Ochoa de Olza)

PAMPLONA, Spain (AP) — Thousands of revelers crammed into the main square and adjacent narrow streets of northern Pamplona on Sunday for the start of Spain's famed San Fermin running of the bulls festival — a potent mix of adrenaline and alcohol-fueled celebrations that span over a week.

The fiesta, an uproarious blend of hair-raising daily bull runs and all-night partying, was immortalized in Ernest Hemingway's 1926 novel "The Sun Also Rises." The event still attracts huge crowds — and headlines of people being injured by the bulls — every year.

Revelers wearing traditional white outfits trimmed with red neckerchiefs and cummerbunds gathered for the noontime launching of a firework rocket, which signals the beginning of the nine-day festival.

Anti-bullfighting demonstrators, with their bodies covered with blood, right, protest against the bull runs on the Ayuntamiento Square in Pamplona northern
Anti-bullfighting demonstrators, with their bodies covered with blood, right, protest against the bull runs on the Ayuntamiento Square in Pamplona northern Spain, Saturday, July 5, 2014. On July 6, the San Fermin festival will begin with the ''txupinazo'' , the opening ceremony with people participating in bull runs, music and dance, through the old street of the city. (AP Photo/Alvaro Barrientos) (Alvaro Barrientos/AP)

Pamplona is located just south of the Rioja vineyard region, and wine has for centuries played an important role in the celebrations, which commemorate the city's patron saint.

On Sunday, festival-goers drank from traditional leather wine pouches, or delighted in spraying the liquid over each other. Others poured wine from balconies overhead.

The first of eight bull runs is set to begin at 8 a.m. (0600 GMT) Monday when thousands of thrill-seekers will aspire to run alongside six fearsome bulls down a narrow 875 yards (800 meters) course through the city's streets.

Late in the afternoon the bulls will face matadors and be killed in the ring.

Dozens of people are injured each year in the runs. Most get hurt after tripping and falling in the rush, but some are gored and trampled by the large, muscle-laden beasts.

The fighting bulls used in the centuries-old fiesta can weigh up to at 1,380 pounds (625 kilograms) and have killed 15 people since record-keeping began in 1924.

The regional government of Navarra said this year's festivities would be patrolled by 3,500 police to keep the events as safe as possible.

A butterfly rests on the finger of an anti-bullfighting demonstrator a she protest against the bulls runs, while displaying a banner which reads,
A butterfly rests on the finger of an anti-bullfighting demonstrator a she protest against the bulls runs, while displaying a banner which reads, ''You Run. Bulls Die'', on the Ayuntamiento Square in Pamplona northern Spain, Saturday, July 5, 2014. On July 6, the San Fermin festival will begin with the ''txupinazo'' , the opening ceremony with people participating in bull runs, music and dance, through the old street of the city. (AP Photo/Alvaro Barrientos) (Alvaro Barrientos/AP)

Animal rights activists protested Saturday, warning that 48 bulls are killed at the festival each year.

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Heckle reported from Madrid.