Violent protests have erupted in China after the death of a teenage boy sparked accusations of a cover-up by authorities, videos from the northwestern region of Shaanxi have shown.In videos verified by CNN, dozens of protesters are seen confronting a wall of riot police outside the Pucheng Vocational Technical School, with some hurling batons and other objects towards the officers.One of the protesters was seen hurling a fire extinguisher at a door, shattering its glass. In response, police are seen aggressively handling the demonstrators, beating some and throwing...