The second day of bull runs at the San Fermin festival in the northern Spanish town of Pamplona left five people injured, including one with a minor goring yesterday, Spanish health officials said.

The injured list consists of two Americans, aged 23 and 46, with the latter suffering from a serious injury after being gored in the neck, according to a medical report from the Navarra regional authorities. The 23-year-old and a Spaniard were also gored in the left thigh but weren't seriously injured during the bull run, one of the most crowded events of the weeklong San Fermin festival. Another runner was treated for bruises, and a fifth was gored in the back by a horn but didn't need hospital treatment.

Prior to the event, a warning by the Red Cross in Spain specifically mentioned how dangerous things could get because of the large number of participants. Since 1911, 16 people have been killed in the event. The most recent death was in 2009.

Each morning during the weeklong festival, six bulls are released from a corral to run through the narrow streets of Pamplona as hundreds of people dressed in white shirts and red scarfs try to race the bulls to the city's bull ring. From there, the animals are killed by matadors in bullfights for entertainment purposes. Eight bull runs are held in Pamplona every July. The festival was immortalized in Ernest Hemingway's 1926 novel "The Sun Also Rises" and has been a vital element of the Spanish culture for more than a century.