The hero teenage boy who walked 13 miles in the desert to get help for his bleeding siblings after Mexican cartel gunmen opened fire on them last week has told how they spared his life by telling him to lie on the ground before driving away after slaughtering his mom and two brothers.  

Devin Langford, 13, was in a car with his mother and siblings when the gunmen sprayed bullets on his family in the Mexican state of Sonora last week. Nine people died in the massacre, which FBI sources say was a 'targeted assassination' but for which no motive has yet been given.  

Police continue to investigate why the family, which had been living in a self-contained religious community for years, became the drug gang's victims. 

Among those killed was his mother, Dawna, and two of his siblings. The others - including his baby brother - were injured.