The BBC's Alasdair Sandford: "Pamplona's streets explode in a mass of moving red and white"

The festival involves hundreds of young men traditionally dressed in white with red neck scarves and armed only with rolled up newspapers, making an 800-metre dash through the streets of the old city of Pamplona to the bull ring.

One Spaniard suffered head injuries after being knocked over and trampled.

Another was carried down the street on a bull's horn which speared the back of his shirt, before being dumped and trampled.

Six fighting bulls, accompanied by six ordinary steers, run through the old town's cobbled streets every morning of the nine-day fiesta from a small overnight corral to the bull ring.

In the evening, all the bulls are killed by matador during the evening "corrida".

Of the 500,000 visitors estimated to be in Pamplona, the vast majority had been on an all-night drinking spree.

Slow death

The San Fermin festival, in honour of the Navarre capital's patron saint, attracts hundreds of thousands of foreign visitors every year since the bull running ritual was made famous in Ernest Hemingway's novel The Sun Also Rises.

But every year, there are scores of serious injuries. The last fatality occurred in 1995 when a 22-year-old American was gored to death, but only 13 of the hundreds of thousands of runners have died at the festival in this century.

Animal rights campaigners have repeatedly called for a ban on the slow torture of the bulls at the end of each run.