At least six women were among the dead, The Houston Chronicle reported. Many of the bodies were mutilated, and investigators said there were at least 49 and possibly more.
The bodies were discovered in Cadereyta, a petroleum-refining center a few miles northeast of Monterrey and about 80 miles southwest of the U.S. border on Highway 40. Monterrey, an inland city in northeastern Mexico, has become an important storage site and transshipment point for drugs moving to the United States.
The Gulf Cartel and the Zetas have been fighting for control of the Gulf Coast region with high body counts on both sides.
Police said the bodies were discovered at about 3 a.m. Sunday, CNN reported. CNN was told posters at the site referred to the Zetas, while the Chronicle said the letter Z was scrawled on walls.