A Spanish village's attempt to invent a "cruelty-free" version of bull-running by replacing the animals with giant balls has ended in tragedy after two people were seriously injured.

One man was left in a coma after sustaining a serious head injury when he was crushed against metal barriers by the 300-kilogramme resin ball which chased runners around the town of Mataelpino, near Madrid during the event over the weekend.

Another man suffered three broken ribs and concussion.