Not all of the facts are in yet, of course, so there is no way to be certain what happened. But it would not be surprising if the liberalized flow of Mexican truckers across the border made possible by the Eightball Obama administration and the whole Open Borders faction of government and business helped to make this sort of thing possible. Truckers can now move freely over the U.S. borders in many states and since they can often make a lot more money smuggling drugs or human beings over the boarder than cilantro or tomatoes, they have strong financial incentive to do things like this.