Violent clashes between police and unionized teachers who were reportedly blockading roads and burning vehicles in southern Mexico left four people dead. The radical union, which goes by the initials CNTE, is opposed to the mandatory testing of teachers as part of the government’s sweeping education reform.

It is also protesting the arrest of union leaders on money laundering and other charges. Yesterday’s clashes in municipality of Nochixtlan in southern Oaxaca involved federal and state police. A member of the CNTE’s political commission said, three people supporting the protests were killed. A state official said, a Oaxaca state police officer was also killed.