Five runners have been taken to hospital after the sixth bull run at the San Fermin festival in Pamplona, Spain.

Although the run itself was without major incident, one participant was knocked unconscious by a Jose Escolar bull inside the ring at the end of the event.

In the festival's "encierros", or bull runs, fighting bulls are set loose in the streets and then race to reach the bullfight arena. Hundreds of aficionados, many wearing traditional white shirts with red scarves, run with them.

Thousands of spectators lined the route of the annual 850 metre dash through the streets of the Spanish old town.

The festival lasts for one week in early July.

Participants sprint next to a Jose Escolar Gil fighting bull during the Encierro (running of the bulls), during the San Fermin festival in Pamplona. - Reuters

Participants are occasionally gored at the hundreds of such bull-running fiestas in Spain every year. Other injuries are common. At least 16 runners have lost their lives at the Pamplona festival down the years, the last in 2009.

As well as the morning bull runs and afternoon bullfights, the San Fermin festival features round-the-clock singing, dancing and drinking by revellers.

Superstitious runners touch an image of the patron saint San Fermin before the run.

There are also religious events in honour of the saint.