One correction, strictly speaking, the M14 is a main battle rifle and not an assault rifle. The former Marine, turned FBI, was armed with the M4 carbine, an updated version of the CAR-15/XM177E2 project from Vietnam days and is a variant of the military M16 assault rifle. This is a link to a photo of the entire M4 system including the M203 grenade launcher and PVS4 night vision sighting system
http://www.fas.org/man/dod-101/sys/land/M4w-att.jpg
As far as laying blame where due, I consider it quite appropriate. This was NOT an accident. The gun did not accidentally go off. The agent intentionally pulled the trigger. This was an avoidable incident due to inadequate or faulty training. This is not the first time something like this has happened with gung ho former military FBI agents. Randy Weaver's unarmed wife was shot and killed while holding her baby by FBI sniper Lon Horuchi(sp?). These personnel are 'experts', as doctors are considered experts in medicine, and as experts they are held to a higher standard of care regarding their actions. When they fail in this care people die and that is unacceptable. As I stated earlier, this was not an acceptable use for FBI SWAT trained personnel.
No snap judgement on my part. I grew up around this my entire life. My father spent 9 years Air Force OSI then 21 years FBI and was part of a counter airline hijack unit. I know when mistakes are made. There is no excuse that can justify the shooting in the face of 20 year old Eagle Scouts at roadblocks manned by FBI SWAT members. I would cut them much more slack if this was the first time something like this had happened. It wasn't. My fear is that still nothing will be done to keep it from happening again.
I believe that the victim will survive, he must be stabilized and evaluations done before any of the multiple surguries he will need may begin. You can bet that this incident will have a profound effect on how he will be able to live his life for many years to come.