The bull had stopped in the middle of the Sarasate de Castejón street after baying spectators had begun waving a banging their hands against the barricades in an effort to whip the beast into a frenzy.
But the crowd got more than they bargained for when one particularly impatient spectator took a long wooden stick and attempted to jab the bull in the face.
With a sudden burst of speed, the enraged bovine leapt over the fence, causing pandemonium and sending the audience scrambling in horror to evade its charge.
One unlucky local resident, Fernando Miguel, 61, attempted to evade the cow's wrath by squeezing himself between the barricades.
He managed to avoid being gored by the bull's horns, but the sheer force of the passing beast caused him to lose his balance, sending him toppling over backwards.
The back of his head hit the road with a sickening crack, knocking him out cold.
The horrified crowd gasped as Fernando lay motionless on the pavement, before concerned onlookers ran over and swiftly whisked him out of shot.
But Fernando wasn't the only casualty of the bull's wrath.
As the beast crashed into the protective barrier, it unleashed an unexpected blow to the gut on 82-year-old Teresa Martínez Pascual, who was also sent crashing to the turf clutching a wounded stomach.
Although her injuries were described as more serious, she was treated by local medics and successfully transported to a nearby hospital in a stable condition for further care.
Fernando meanwhile later regained consciousness and despite having suffered a severe cranial contusion escaped serious injury and was discharged from hospital later that night.
The man who incited the bull's anger by poking at its face with the stick was unhurt in the incident, his actions having only caused significant injury and pain to his compatriots.