Three people have died and 45 others were injured in a violent clash between members of a dissident teachers' union and police in southern Mexico.
Emergency services officials confirmed the deaths in Oaxaca state on Sunday, as police continued to remove protesters who are blockading a highway and hampering the operation of a local oil refinery.
Mexico's National Security Commission says 21 federal and state police were wounded in the clashes, of which the cause is still not clear.
Federal police have had to escort 120 trucks carrying chemical waste from the state-owned refinery, with the operator saying it would have to shut down operations if the blockade continued.
The clash, which involved masked protesters throwing rocks at police who responded with tear gas, escalated several days after supporters of a splinter teachers' union took over a highway near the town of Nochixtlan, about 80km northwest of the state capital, Oaxaca City.