An improvised propane bomb is the most likely device used by the person behind the Christmas Day bombing in Nashville.

Nashville PD has released a high-resolution video of the explosion that can be viewed here. As a technical note, the camera may be a city camera used to monitor accidents at the intersection. The video does not offer a fast frame rate that would allow for a much closer examination of the blast.

SOFREP has viewed and analyzed several videos of the explosion and makes the following observations.

First, the explosion shows a bright fireball that evaporates very quickly and cleanly without much smoke dust or debris vaporization. This suggests that fuel, rather than explosives like C4, Dynamite, TNT, black powder, or ammonium nitrate, provided the source of the blast.

Hollywood explosions use lots of kerosine fuel, which creates big fireballs for dramatic effect, but they consume themselves and burn out very quickly. Propane creates extreme heat — on the order of 2,000 degrees Fahrenheit. It burns very cleanly with very little (even less than kerosene) smoke or residue. This is why propane is the preferred source of outdoor grills. But it is not ideal as an explosive.