Six people were hurt on Sunday in Spain's traditional annual San Fermin bull running festival, with one participant gored and five suffering bruising, local government sources said.

A 37-year-old Spanish man emerged from his goring with slight injuries, officials said.

The curtain went up on nine days of festivities on Saturday as thousands of revellers dressed in white clothes and red scarves filled the city's main square for the "chupinazo" -- the firecracker which launches an event dating back to medieval times.

The run became world famous after being immortalised by US writer Ernest Hemingway in his novel "The Sun Also Rises" in 1926.

The festivities include concerts, religious processions and copious amounts of wine.

Each day at 8:00 am hundreds of attendees launch themselves into a dangerous 850 metres (930 yards) race, seeking to outrun -- or at least avoid -- six heavy fighting bulls through the city centre's narrow streets. 

During the intense "running of the bulls", which lasts less than three minutes, the runners try to get as close as possible to the animals in their sprint to the Pamplona bullring, where bullfights are held in the afternoon.

This year's edition saw the day of San Fermin fall on a Sunday, allowing a stronger turnout than when the saint's day falls on a weekday. 

Anyone aged 18 or above may participate.

Dozens of people are injured each year, although most are injuries resulting from falls or being stomped by animals. To date, 16 deaths have also been recorded since 1911, the last coming in 2009.