MONTERREY, Mexico – Forty-nine bodies with their heads, hands and feet hacked off were found Sunday dumped on a northern Mexico highway leading to the Texas border in what appeared to be the latest carnage in an escalating war between Mexico’s two dominant drug cartels.

Local and federal authorities discovered the bodies before dawn scattered in a pool of blood at the entrance to the town of San Juan, on a highway leading from the metropolis of Monterrey to the border city of Reynosa. A white stone arch welcoming visitors was spray-painted with black letters: “100% Zeta.”

Nuevo Leon state security spokesman Jorge Domene said at a news conference that the 43 men and six women would be hard to identify because of the lack of heads, hands and feet. The bodies were being taken to a Monterrey auditorium for DNA tests.

The victims could have been killed as long as two days ago at another location, then transported to San Juan, a town in the municipality of Cadereyta, about 105 miles west-southwest of McAllen, Texas, and 75 miles southwest of the Roma, Texas, border crossing, state Attorney General Adrian de la Garza said.

Only one couple looking for their missing daughter visited the morgue in Monterrey where autopsies were being performed on the mutilated bodies Sunday, a state police investigator said.

The officer, who spoke on condition of anonymity because he was not authorized to discuss the case, said none of the six female bodies matched the missing daughter’s description. He said some of the bodies were badly decomposed and some had their whole arms or lower legs missing.

De la Garza said he did not rule out the possibility that the victims were U.S.-bound migrants.

But it seemed more likely that the killings were the latest salvo in a gruesome game of tit-for-tat in fighting among brutal drug gangs.

“This is the most definitive of all the cartel wars,” said Raul Benitez Manaut, a security expert at Mexico’s National Autonomous University.

Mass body dumpings have increased around Mexico the last six months as the fearsome Zetas gang goes head to head with the powerful Sinaloa Cartel, led by fugitive drug lord Joaquin “El Chapo” Guzman, and its allies.

Under President Felipe Calderon’s nearly six-year assault on organized crime, the two cartels have become the largest in the country and are battling over strategic transport routes and territory, including along the northern border with the U.S. and in the Gulf coast state of Veracruz.