The child was gored in the buttocks and abdomen by the bull during the annual festivities in Alfamén, a town near Zaragoza in northeastern Spain, on Monday.
The bull broke through metal barriers lining the street to protect onlookers during the encierro – when daredevils run alongside bull on a route through the town ahead of the evening's bullfight.
Alejandro Gil, the mayor of Alfamén insisted all safety regulations had been met but the bull broke through a lock on the barrier in what was a “horrible accident”.
Luckily the girl, a resident of the town, suffered no damage to vital organs and after being treated by paramedics at the scene was transferred to the children's hospital in Zaragoza where her condition was described as “serious but stable”.
On Tuesday a woman died after falling down an escarpment during the first encierro of the fiesta in Falces, Navarra, which takes place in a hilly area on the outskirts of the town.
The 53-year-old suffered chest and head wounds as a result of the fall and died the next day in hospital. Hundreds of towns and villages celebrate bull running festivals across Spain each summer.
Last year 14 people died in gorings while this year at least four spectators have already been killed, including a woman who accidentally stepped into the path of a rampaging bull from the doorway of a house in Moratalla, a town in Murcia, southern Spain.