Several thousand thrill-seekers have tested their bravery by dashing alongside six fighting bulls through the streets of the northern Spanish city of Pamplona on the first day of the running of the bulls at the annual San Fermin festival.

Despite a large crowd of runners, only two people were treated for injuries and no one was gored.

Red Cross spokesman Jose Aldaba said one person was taken to hospital with a left arm injury and another was receiving treatment for a shoulder dislocation.

There was a moment of tension as the last bull of the pack became disoriented and turned around to look back at runners, but it eventually entered the bullring without charging at anyone.

The nine-day fiesta was immortalized in Ernest Hemingway's novel The Sun Also Rises.