Spanish Red Cross spokesman Alfonso Contin today said that two men were treated for minor injuries suffered in falls.
Many runners fell along the wet, cobble-stone route. Some were trampled on by the half-ton beasts.
The runners test their agility and bravery by racing with six fighting bulls along a 850-meter course to the city's bull ring.
The hair-raising "encierros", as the runs are called in Spanish, last three minutes.