A runner was gored in the face and many more were fortunate to not be seriously injured during a chaotic bull run at Spain’s San Fermin festival.

The six bulls and accompanying steers charged through crowds of thrill-seekers who packed the narrow street course in Pamplona.

The huge animals knocked down bodies to the cobblestones, and stumbling runners caused several pile-ups during the two-and-a-half-minute run from the pen to the bull ring where bullfighters will kill the bulls later in the day.

An injured girl is carried on a stretcher by Red Cross health services . Photo: AAP

One runner was pierced by a horn in the face, while 12 more people needed medical treatment for an assortment of knocks, according to the University of Navarra Hospital.

A black bull broke away from the pack early in the 875-metre run and ploughed into a group of people, smacking one full in the side of the face with a horn. It was not clear if that was the moment of the goring.

Many runners appeared completely unaware when bulls were breathing down their necks and, instead of trying to gore them, just shoved them out of the way.

Saturday’s was the fifth morning run of the eight-day festival in northern Spain.

A ‘recortador’ jumps over a bull during the San Fermín festival in Pamplona. Photo: AAP

This year’s festival comes 100 years since the publication of Ernest Hemingway’s novel The Sun Also Rises, whose publication launched the San Fermin festival to international fame.

The last death at San Fermin’s bull runs occurred in 2009, but gorings and broken bones are common, partly due to the large number of novice bull runners and foreign tourists who join the experienced locals.