That's pretty much the story around here too. I was hiking a lightly traveled trail in the Santa Rita Mountains and encountered a "pack train" of about 20 mules and bales. Fortunately, I saw them first and was able to get off the trail into a thicket. The guy in front and the guy in back were both carrying AK-47's. The rest were just carrying weed, from what I could see.

The smugglers will try to steal dope from one another and fire-fights between groups of smugglers are not uncommon along the border. Near Tumacacori, which is close to my home, there were 3 people killed in a recent drug shootout. The dopers are known to shoot first and then ask questions. Most of the illegals are not looking for trouble and will avoid you if at all possible; they are just trying to find work.