McALLEN, Texas (Border Report) — The hacked-up remains of 27 people have been found in several graves in the northern Mexican border town of Reynosa, just south of McAllen, Texas, according to several reports.

Some corpses were buried so recently that tattoos remain visible on some skin parts and investigators are using those designs to help identify four of the bodies, according to the Associated Press. But most were hacked into multiple pieces, according to the leader of a search group called Colectivo Amor por los Desaparecidos en Tamaulipas (For the Love of the Disappeared).

The bodies were found about 4 miles from the border in the northern Mexican state of Tamaulipas, which has long been a stronghold for various drug cartels and splinter groups vying for power and control of drugs and human trafficking across the Rio Grande.

CNN reports that the Tamaulipas Attorney General’s Office is investigating the finding of these bodies.

The remains reportedly were found in 20 graves located in Tamaulipas starting on Sunday. AP reports that some of the burial pits contained multiple bodies “and that the clandestine burial site may have been used by gangs as recently as a month or two ago.”

Drug cartels and gangs are known to bury victims in mass graves. These bodies reportedly were found just 18 inches below the earth.

The Associated Press and CNN contributed to this report.