Two men were gored during the Running of the Bulls in Pampaloma, Spain, including a man from Chicago who co-wrote a book on how to survive the run.
Bill Hillmann, 32, tripped and fell when a bull gored him in his thigh.
It happened today during the third of seven runs.
Hillmann travels to Pamplona every year to take part in the week-long festival.
The bull that gored Hillmann was the largest of the six bulls in the run.