EL PASO, Texas (Border Report) – The search for a group of migrants missing for 11 days near the Ojinaga, Mexico-Presidio, Texas border has come up empty, Chihuahua state authorities said.

However, the aerial reconnaissance and ground sweep of the desert near the town of Coyame yielded two burnt vehicles and numerous spent shell casings. The vehicles aren’t believed to be related to the migrants, said Enrique Rodriguez, a spokesman for the Attorney General’s Office.

The migrants set off for the United States from Aldama, Chihuahua, on or about Sept. 25 with the intent of finding work in the Odessa, Texas area, according to authorities. A teenager who traveled with the group has told police armed men intercepted the vehicle the group was traveling in near the town of Coyame. The boy said the men tied up the migrants, beat up their two guides and allowed him to escape.

A total of 13 people remain missing, the Attorney General’s Office says.

The Presidio-Ojinaga area is a known drug and migrant smuggling corridor where the drug gangs are aggressively trying to take control of the migrant trade as well, according to authorities on both sides of the border.

No bodies were found inside the burned vehicles — a 1999 Dodge Caravan and a 2000 Dodge Ram, authorities said. A newspaper in Ojinaga published photos of the abandoned vehicles.