The border is as it's always been, a hard and dangerous place. It's is not getting worse but you should not expect it to get better either.
If you are serious about this you need to do some research. start with image searches of "USBP Rocking" or "USBP Rock attacks." Follow that with searches of "Brian Terry," "Kris Eggle," "Theodore Newton" "George Azrak" and many others. One of my former co-workers has a six inch scar on the side of his head where his skull was fractured by three IA's who jumped him with rocks as impact weapons. Luckily he is a tough SOB and managed to get to his GP-100, killing one and wounding a second. The GP-100 should give you a clue this is nothing new.
There are some illegal migrants who simply want a better life. They are not the problem in this case, in fact, they are just another commodity to be smuggled and exploited. They will be held hostage and ransomed back to their families, sold into sex trafficking, or even stolen /kidnapped from one group of thugs by another group of thugs. "Family Groups" may not be family members but rather IA's traveling with children they have rented to avoid being detained for extended periods of time or smugglers bringing in kids. Sometimes to be re-united with family members already in the U.S., sometimes for other, darker purposes. IA's are regularly robbed, raped, murdered, or die of environmental conditions such as Heat, dehydration, hypothermia after being abandoned by their smugglers.
Some migrants are previously deported felons and gang member there are usually a few in each group of any size. Then there are the smugglers and the backpacker mules. Make no mistake, they are hardened criminals, as dangerous as those in the worst urban neighborhoods in the U.S.. USBP deals primarily with the smuggling groups many of which can be traced back a hundred years. These smuggling groups often use criminal street gangs and prison gangs as foot soldiers here in the U.S.. When USBP is mentioned people think illegal aliens but USBP actually seizes more drugs than any other federal agency.
I believe the suspects will turn out to be a crew with a drug load or previously deported IA's with criminal history in the U.S..