Thousands of university students scuffled with police and government supporters during a protest Tuesday demanding that civil liberties be respected under constitutional reforms being drafted by allies of President Hugo Chavez. Police tossed tear gas canisters into the crowd of opposition students after clashes broke out with a smaller group of pro-Chavez demonstrators near the National Assembly. Journalists estimated the crowd at about 20,000 protesters, but pro-Chavez lawmakers said there were far fewer. There were no reports of arrests or serious injuries, though student leader Stalin Gonzalez said at least five demonstrators suffered minor injuries during the bottle and rock-throwing melee.