Similar explosion in 1947 in Texas City, Texas which witnesses also claim looked like a nuclear explosion and was the largest explosion ever in the U.S. The Sodium Nitrate explosion claim seems likely.
@NavyCanDo Static electricity can set this stuff off if it is stored in an enclosed space with no air circulation in weather this hot.
These silos MUST be grounded as well as have ample air circulation.
The explosion could have came from something as simple as a circuit that controls the fans was shorted out. Yeah,there are SUPPOSED to be controls with warning lights and physical checks,but the reality doesn't always match with the "supposed to be".
As for Trump's response, he's already claiming it was a bomb. Way too soon for him to be making the claim that it was an attack.
Unless he already knows something the rest of us don't know,I agree. It ain't like waiting a day or two for evidence to show up before popping off would hurt anything. After all,this ain't politics UNTIL AND UNLESS it is determined to have been an act of terrorism.