Mexican authorities say they have discovered the bodies of seven men dumped on a road in a region popular with tourists.

Authorities say the bodies of seven men were found dumped on a roadway late Thursday in the Huasteca region with extensive bruising that suggest they were beaten.

Writing scrawled in markers on the corpses said "this is what happened to me for working with the Gulf," an apparent reference to the Gulf cartel, which operates mainly along the U.S. border to the north.

The messages were signed "Valles Operation O.B.," apparently a reference to a rival gang.

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A police officer walks amid ammunition near the scene of a shooting in Mexico City, Mexico

Prosecutors in San Luis Potosi state said late Thursday the bodies did not appear to be from the township of Aquismon, and may have been killed elsewhere and dumped in the rural area

The Huasteca region has long been popular with Mexican tourists for its waterfalls and crystalline rivers.

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Cartel violence is also being blamed for simultaneous shooting attacks at two bars in north-central Mexico in late May that left 11 people dead. 

Handwritten signs left at the scenes of the killings suggested the attacks were part of a rivalry between two drug cartels that have been battling for control of Guanajuato state for several years.

A damaged pick up marked with the initials C.D.N., that in Spanish stand for Cartel of the Northeast (AP Photo/Gerardo Sanchez)

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Fox News contributor Tom Homan, former Acting Director of the U.S. Immigration and Customs Enforcement, warned earlier this month that cartel violence will continue to spread into the United States as a result of the Biden administration's lack of immigration enforcement at the southern border. 

"The most treacherous territory is where the convicted criminals and the drug dealers try to move their drugs, because it's harder to apprehend them," Homan told "America Reports." 

Huasteca region, Mexico.

Shops in shopping street in the city Xilitla, San Luis Potosi, Huasteca region, Mexico.  (Photo by: Marica van der Meer/Arterra/Universal Images Group via Getty Images)

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Homan continued, "You know, only with use of a drone can you see them coming. So, yeah, you're going to see populations across the entire southwest border. Every sector is going to see an increase because the cartel is going to spread their madness out, right? They're going to send large groups to a certain area knowing Border Patrol is going to surge resources there. And that's where they're going to move the drugs and the convicted criminals, the pedophiles. This again, it's a worst-case scenario. This administration has sold out our national security."

Associated Press contributed to this report.