There are many incidents of armed military types from Mexico entering U.S. and skirmishing with Border Patrol. They have fired on BP and rammed BP vehicles. It is an organized effort to help smugglers.
So far there has been no response that I have heard of to these incidents officially by our government. It seems when an incident of this type happens- it is news in a limited area and then poof it goes away.
It's a shame that coudn't have happened to the dump truck.
I truly would love to read... "A small explosion was heard on the border earlier today. It's reported to have been a small dump truck illegaly trying to enter the US. Us forces deny any involvement."