As the first anniversary of the enforced disappearance of the 43 Ayotzinapa students approaches, protests and tensions are building. Yesterday, police in the state of Guerrero, where the abductions took place, blocked family members and classmates of the Ayotzinapa students from proceeding along the highway to Mexico City, where they plan to join protests in the nation's capital. Six police and 12 students were injured in clashes. Clayton Conn reports from Mexico City. teleSUR