But none of the several thousand daredevils testing their bravery by running beside six fighting bulls were gored in today's race.
Dr Oscar Gorria says three runners have been hospitalised with head injuries and one was being treated for a chest injury.
There were dangerous moments when one bull tossed two runners, but it narrowly missed them with the points of its horns.
The festival blends adrenaline with all-night partying, and 15 people have died from gorings since record-keeping began in 1924.