The second large explosion/flash blast erupted vertically as if from a wide-diameter hole in the ground - perhaps a large underground fuel reserve.
Both the first and second of the large explosion/flash blasts, carried with them, enormous amounts of fuel of some type, that continued to burn in their respective ball/mushroom formations.
Update:
https://twitter.com/Militarylandnet/status/1658166369416798213
“The facility hit on May 13 near the city of Khmelnytskyi was an aviation missile and ammunition depot, military unit A3013.”