Apparently, Ukrainian drones pushed through and started a chain reaction.
Explosions reportedly continued for hours, and authorities evacuated nearby settlements. Initial reports indicate that the site, previously protected by one of Russia’s densest air defense networks, suffered catastrophic damage.
Neither the article in the OP nor the Business Insider article claim that it was an attack by Ukraine. The BI article says that Ukraine hasn’t commented on the explosion:
I’m not saying they didn’t do it, or that the accident explanation isn’t propaganda, just pointing out that OP mayhaps is pulling this out of their ass: