ROUGH CUT (NO REPORTER NARRATION)<br/> <br />STORY: Student groups clashed with police in Mexico City on Sunday as hundreds of demonstrators attempted to block Congress to keep lawmakers from entering for their opening session.<br/> <br />Clouds of tear gas filled the street in front of Congress as riot police advanced on the protesters.<br/> <br />The young people, who came largely from the anti-government group "I am 132", covered their faces and shouted slogans such as: "Not one more step back" and "Out with Pena Nieto", referring to Mexico's President Enrique Pena Nieto.<br/> <br />They threw rocks, sticks and Molotov cocktails as they tried to block Congress, which was guarded by hundreds of federal police officers.<br/> <br />Initial reports said that two police officers were injured and taken to the hospital.
