Doesn't even need to be mercenary soldiers. Could simply be a couple of America haters who specifically picked a country music concert to shoot up (from two different windows simultaneously).
An alleged neighbor of the alleged shooter called into the Savage Nation today.
"Rick" (was in the marine corps) was a neighbor in Mesquite, NV for 7-8 months. He says 100% this guy isn't the "type." He drank beer with the guy. Says the alleged shooter was a Trump fan. He told Clarke county sheriff's office everything he knows.
Related...
UNIDENTIFIED OFFICER: "We have sight on the suspect's door. I need for everybody in that hallway to be aware of it and get back. We need to pop this and see if we can get any type of response from this guy. See if he's in here or if he's actually moved somewhere else."
The guy had been dead (how long?) prior to LEO's entering the room.
http://talkingpointsmemo.com/news/police-officers-killed-dallas-shooting