[KMag]

Yes, particularly ammonium nitrate (or another nitrate) without enough fuel to consume the excessive oxygen released when the nitrate decomposes. Nitrogen dioxide is that deep red-orange. It's the most common oxidizer in hypergolic rocket motors (though, they pressurize and cool it to get it to largely dimerize dinitrogen tetroxide). The other oxides of nitrogen produced by ammonium nitrate decomposition are basically colorless. Hot nitrogen dioxide would have pretty much instantly oxidized any fuel present, releasing more energy and dramatically toning down that deep red-orange color.

This is good evidence against an intentional detonation. Even if it were arson, it probably wasn't an intentional detonation. It's inconceivable that anyone with enough research to successfully cause an ammonium nitrate detonation wouldn't have run across the fact that any of a number of cheap organic fuels increase both the power and reliability of ammonium nitrate explosions. So, it's very unlikely this was an intentional explosion, unless they were trying to make it look like an accident. If they were trying to make it look like an accident, then the objective wasn't to generate fear in the populace / political change, and any conspiracy theorist then has the problem of having to figure out what the specific target was, since we can rule out the general populace. This should put most conspiracy theories to rest, at least without silly statements by the tweeter-in-chief.