One man had a lucky escape when he confronted a lone bull that had broken away from the pack after a fall but he was only rolled on the ground and not caught by its horns.
He was taken to Navarra Hospital and identified by city authorities in a statement only as a 26-year-old Irishman, Adam C.H.
The fifth bull run in the eight-day San Fermin feast took place the day after a 27-year-old man was gored to death, the first since 1995.
Virgen del Camino Hospital spokesman Dr. Fernando Boneta said five people suffered head injuries Saturday and were admitted for medical treatment but none was seriously hurt.
One man was hit hard on the chin and knocked unconscious by a calf inside the bullring after the running of the bulls had finished.
Among the injured was a 48 year-old American identified only by the initials C.R.D., who was waiting to be released from Virgen del Camino hospital after being treated for a head wound, and a 22-year-old Spaniard, the statement said.
The bulls Saturday belonged to breeder Dolores Aguirre, famed for producing hefty, strong animals. The largest of the six animals weighed in at 1,378 pounds (625 kilograms).
The runs start at an overnight enclosure half a mile (850 meters) away from the city's bullring where the animals face matadors and almost certain death each afternoon of this ancient fiesta.
The pack races along the often damp cobblestone course accompanied by six steers, each with a large clanking bell around its neck, whose function is to try to keep the group trotting together.
The greatest danger happens when the pack splits up, leaving bulls disoriented and irritated by crowds composed of thousands of adrenaline-charged
- and often alcohol-fueled - thrill seekers.
Despite the large number of runners and the separation of one bull from the pack, all of Aguirre's animals entered the ring in 2 minutes 52 seconds, a reasonably fast time.