EL PASO, Texas (Border Report) – Mexican officials say a fight for control of migrant smuggling might be behind the murder of eight men whose naked bodies were abandoned on the side of a busy highway leading to the U.S. border.

Multiple motorists on the Chihuahua-Juarez Highway reported the bodies to police early Sunday 20 miles north of Chihuahua City.

First responders found the victims with multiple stab wounds and some with signs of asphyxia; a sign from an unidentified criminal group was left at the scene warning rivals to stay away from Chihuahua, police confirmed. The sign quoted a song associated with the state of Sonora, one of the bastions of the Sinaloa cartel.

“We found a burned vehicle (18 miles) to the north that could be related to this event. They used it to move the bodies,” State Public Safety Director Gilberto Loya told a Border Report camera crew. “We have a precedent of homicides committed in that area directly related to human trafficking.”

Migrants by the hundreds of thousands have passed through Chihuahua in the past five years on their way to the U.S. border. In recent months, as Mexican federal officials have cracked down on migrants riding cargo trains from southern Mexico to Juarez, migrants have converged on makeshift tent encampments in Chihuahua City before walking, hitching rides or paying to be taken to Juarez.

Also on Monday, Chihuahua Attorney General Cesar Jauregui told reporters two victims have been identified as residents of Sinaloa, and that the burned vehicle was traced to them. The two possibly had been abducted days earlier.

Chihuahua, which borders Texas and New Mexico, in the past few years, has been a battleground between gangs associated with the Sinaloa cartel and La Linea, the strongest of the remnants of the old Juarez cartel. The newspaper El Diario last week reported that three criminal groups control migrant smuggling in the Juarez corridor, with La Linea claiming most of the El Paso border, La Empresa operating to the west and Sinaloa holding on to everything east of the city.