Mexico City -- Mexican authorities said Thursday that 21 bodies, some burned, have been found in the northern Mexico border state of Tamaulipas in what appears to have been a clash between drug gangs. The bodies were found near the remains of seven burned-out vehicles near the border town of Miguel Aleman.

President Andres Manuel Lopez Obrador said the killings Wednesday appear to have been part of a dispute between gangs. He said details would be released once all the information was gathered.

A Tamaulipas state official who was not authorized to be quoted by name said investigators had counted 21 bodies at the scene.

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The area around Miguel Aleman had long been dominated by the Zetas drug cartel, which was locked in a battle for control of crime in the Rio Grande Valley with the rival Gulf cartel.

The Zetas cartel has since splintered, and the deaths in Miguel Aleman appear to have resulted from a dispute between the Gulf cartel and one of the Zetas factions, the Northeast cartel.

Tamaulipas has been a major conduit for drug shipments and has also been the scene of some of the worst massacres and fiercest fighting in Mexico's drug war.

Police guard the scene of a murder after a man was shot to death in Acapulco, Mexico, in this Jan. 2, 2019 file photo AP

That war left 28,689 people dead in Mexico in 2017, according to government statistics -- the highest number ever recorded, and likely was even more deadly.

But as CBS News' Haley Ott discovered in December, there are at least 36,265 more people in the country who have simply vanished amid the bloodshed. Known as desaparecidos, or "the disappeared," some are abducted, others are caught in the crossfires of the cartel-related violence that permeates Mexican society.

Many are presumed dead, but without bodies, their families are left without answers, and sometimes with the grim burden of trying to find their missing loved ones' remains on their own. Watch the full report in the player at the top of this page.