Prosecutors say they cannot determine how many were killed because attackers cleaned up the scene and removed any bodies
Mexicans have been left wondering what happened to about a dozen men who disappeared after they were seen lined up against a wall by drug cartel gunmen.
In a video apparently filmed by a resident of the town San José de Gracia in the western state of Michoaán and posted on social media, bursts of gunfire broke out and smoke covered the scene.
