Animal rights activists clashed with riot police as they protested against bullfighting outside the Santamaria Bullring in downtown Bogota, Colombia on Saturday. /CFP Photo

Bullfighting season, reinstated by order of the Constitutional Court after an absence of more than four years, started Sunday at the historic Santamaria venue. /CFP Photo

Police fired tear gas to control the protesters, who shouted "murderers" while spitting and sometimes coming to blows with spectators nervously making their way to Bogota's 1930s-era brick bullring. /CFP Photo

Animal rights activists held a sign reading "Bullfighting, shame of humanity." /CFP Photo