Four suspects are in custody charged with capital murder in connection with a fatal shooting in Harris County that left one person dead and an undercover Harris County Sheriff's deputy wounded.

Federal drug enforcement agents fear this may be a sign that the murderous drug cartels are moving their violence into the United States.

Officers with several local and federal agencies were conducting surveillance on an 18-wheeler carrying an undetermined quantity of marijuana when several suspects in vehicles pulled up to the truck and opened fire.

Officers quickly returned fire, and when it was over the truck driver was dead and the undercover officer was wounded.  Four suspects, all believed to be Mexican nationals, were arrested and charged with capital murder in connection with the shooting.

Officers were amazed when they found only 300 pounds of marijuana in the truck.  Investigators say while some of the arrested attackers have admitted to an affiliation with the Mexico-based Zetas, they're now trying to figure out why such a risky and brazen attack was launched over such a small amount of marijuana.

via Zeta soldiers launched Mexico-style attack in Harris County - Houston Chronicle.

One theory is that the drug cartel members were expecting to find a lot more marijuana in the truck and they were there to "rip it off."

Another theory is that this was the Zeta's way of "coming out", and letting Houston area dealers know there's a new "cartel" in town.