international human rights groups alleging venezuela's use of colectivo gangs to repress protestors, one of the touchstone examples took place here, at the central university of venezuela. it's a highly politicized campus with a history of fighting between students who support or oppose the government. but on march 19 - with the protests raging - things got out of hand. >> well the human rights watch report says that the attack really started when a man wearing civilian clothes came through that doorway carrying a firearm and threw two tear gas canisters into this lobby, then shouted that the colectivos have arrived. then twenty more people showed up and the students set off running down that corridor. >> these students say they were holding a political meeting that was interrupted by people with guns who chased and beat them. >> this student wanted his identity hidden for fear of reprisals. >> he says a series of colectivo attacks over the past weeks have provoked opposition students to fight back. >> but the revenge attack by opposition students is not mentioned in the human rights watch report. to hear that story, we've come back to the neighborhood tha