The annual bull running festival in the northern Spanish city of Pamplona got off to a dangerous start on Sunday when a number of people were injured in the first dash through the streets.

The city is usually jammed with party revellers

Some were gored by the animals' horns as a number of the bulls slipped on the dew-covered cobblestones on their way to the city bullring.

Partly as a result of this, the 825-metre-run through the narrow, winding streets took over seven minutes - more than twice the usual time.

The San Fermin festival begins on the morning of each 7 July, when thousands of spectators - mostly men - run alongside six bulls from a pen to the arena.

The fiesta was immortalised by Ernest Hemingway in his 1927 novel Fiesta: The Sun Also Rises.

Bullfight extravaganza

Every year, tens of thousands of foreigners flock to the San Fermin festival, but the numbers at the opening run were unusually high because it fell on a Sunday.

The fiesta dates back to 1591

Crowds jammed the city's central square for the traditional firework display that starts a week of round-the-clock drinking, partying and an early morning run with half a dozen fighting bulls.

"Why am I running? I love bulls and I love parties," Rafael, 28, from Valencia told the Reuters news agency.

But only a few hundred of the bravest gather in the old quarter each morning pursued by six stampeding bulls. The fighting bulls are killed by matadors each afternoon.

The bulls usually injure several people each day. Since the start of the last century, 13 runners have been fatally gored or trampled to death.

The running of the bulls dates back to 1591, when its purpose was to move the bulls into the arena.