BNSF agent ? had to look that up ...some kind of Rail road guard ?
RR Police for BNSF, they are legal police officers with arrest powers. If you don't believe that trespass on their property, they will put you in cuffs and take you to the nearest pokey.
Normally they stay to BNSF business, but will do back up in emergencies, in this case had it went different he would have cuffed the guy and called the locals to come take custody.
In this case more drastic action was needed, police say attempted assault was done on people with a non-firearm weapon. Rumor is it was a stun gun.
Word is not official yet but looks like it will go down as a legitimate kill.