Three men have been gored during a bull run in the Spanish city of Pamplona.

A 20-year-old American tourist and two Spaniards were injured as they ran through the cobbled streets of the city as part of the week-long San Fermin festival.

Authorities did not give specific details of the condition of the men, although one of the Spaniards is described as having suffered "less serious" injuries.

A further three runners were injured during the run, including another American. Authorities did not specify their injuries, but participants are often hurt due to falling in the chaotic dash through the city.

The gorings were the first this year at the festival, which started on Sunday and includes a daily bull run starting at 8am that usually lasts between two and five minutes.

Pamplona's San Fermin festival, one of hundreds of bull-running fiestas held around Spain every year, was made famous by Ernest Hemingway's novel The Sun Also Rises and attracts visitors from around the world.

Many participants, traditionally dressed in white with red kerchiefs around their necks, drink all night before the early morning run.

A 27-year-old from Madrid was the last person to be killed during a Pamplona bull run, after being gored in the neck in 2009.

There have been 14 fatalities over the past century at the fiesta that dates from the 13th century.