Venezuelan riot police fired water cannons and tear gas at stone-throwing student protesters in the capital Caracas, leaving at least seven injured.Demonstrators had initially been riled by armed vigilantes they link to thegovernment. Riding motorcycles, the men had fired guns into the air at the CentralUniversity of Venezuela's campus.Students, some of them masked, beat two motorcyclists.The confrontations were the latest violence in two months of near-daily protestsagainst President Nicolas Maduro's government that have seen 39 people killed and 550 injured. Hundreds of opposition and student demonstrators have been detained.A march called by student leaders had sought to leave the university for the officesof the vice president who is in charge of the economy when the national guard andriot police intercepted them.The injured suffered bruises, fractures and open wounds, student leader Hilda RubiGonzalez said, adding that they were all in "stable" condition.At least four photojournalists and cameramen from local media were attacked androbbed, according to the victims and press freedom groups. At night, the historical Caracas district of Chacao, which is an opposition bastion,was the scene of clashes between a small group of masked men armed with stonesand riot police, who responded with tear gas.Protesters are venting their anger over soaring crime, high inflation and shortagesof essential goods.