Pamplona is infamous around the world for the San Fermín festival, in which locals and visitors run through the streets with charging bulls, on their way to the ring.
On Thursday, it was reported that a 19-year-old woman had been raped by five men. Allegedly the attack was recorded.
Since then, a number of sexual assaults have been reported.
Spectators of Monday’s bullfight left the ring quietly and assembled together to protest against the assaults.
Reports of sexual attacks at festivals across Europe have been on the increase this year.