It began as a peaceful protest against bull-fighting in the Peruvian capital, Lima.
It turned into a fight between police and protesters outside the city's main bullring.
Police unleashed tear gas and water cannon against the hundreds of activists who marched on the venue to protest on the opening day of the season.
The demonstrators accused the police of heavy-handedness.
(SOUNDBITE) UNIDENTIFIED PROTESTER SAYING:
"We went to the bullring with a banner that said 'Compassion and justice for Bulls' and they grabbed us and beat us."
There appeared to be no compassion for the protesters among those arriving to see the bullfight.
(SOUNDBITE)(Spanish)UNIDENTIFIED WOMAN SAYING:
"They should go and defend the dolphins who are being exterminated."
Peru's bullfighting season runs from late October to December