I need a hive mind to investigate this. What chemicals were being housed at the AT&T address, 185 2nd Ave N, Nashville TN ? https://goo.gl/maps/qTUsDYmdSTSJrABt6

The RV was parked exactly where this white pickup is parked in this picture. https://imgur.com/a/2b2Rxnc

Which means the RV was parked directly in front of this NFPA 704 placard which indicated dangerous flammable chemicals are inside the AT&T building. https://imgur.com/a/XysjSvC

A description of the numbers and meaning of a NFPA 704 placard are here : https://imgur.com/a/LqyLzQZ

Here is a frame from the recently released body camera footage to show this location : https://imgur.com/a/UZ341C2

THIS IS WHERE I NEED HELP. I have been unable to find what chemicals match the NFPA rating of 3-4-1-W.

Whatever this is, it's rated the highest on the NFPA 704 fire danger scale (4). It can burst into flames at room temperature. It's also an extreme danger to health (3), unstable when heated (1) and reacts with water (W), meaning don't use water to extinguish the fire.

The closest chemical I have found is liquid hydrogen, which is 3-4-0-blank. The difference being liquid hydrogen is stable (0) and doesn't react with water.

I have been unable to locate exact matches to this rating after several hours of searching. If we find out what was stored in AT&T, it might help to understand the explosion, why it was a target, or other factors.