Daniel Ochoa De Olza / AP
Revelers are surprised by an angry leading ox, used to drive the fighting bulls during the running of the bulls at the San Fermin festival in Pamplona, Spain on July 7.
Jesus Caso / EPA
A 'mozo' or runner is turned round by a young bull at Pamplona's bullring after finishing the first run of the 2011 San Fermines festival on July 7.
See more great images of the San Fermin festival in our slideshow.
Two people sustained minor injuries in the annual festival, which takes place in the Spanish city every July. TODAY.com's Dara Brown reports.