Unidentified gunmen ambushed a police squadron outside an isolated village in the southern Guerrero state Saturday, reportedly killing at least four officers.
Mexican media gave conflicting casualty reports ranging from four to seven police officers killed and up to five wounded.
The reports could not be immediately confirmed independently.
The mountainous area has long been the site of bloody conflicts between peasants and police. At least two dozen people have been shot to death in gunfights there.