Whilst in context, I think it’s more likely the ship was hit by Ukrainian missles, I’ve just remembered something that makes the ammo explosion excuse more believable - the sinking of the Kursk submarine.
For those who don’t know, the Kursk was a nuclear powered submarine and a jewel of the Russian Navy. Considered unsinkable, in 2000 it was participating in war games, firing a dummy torpedo where a combination of factor resulted in an explosion in the ammo storage leading to the sinking of the vessel. The other Russian forces didn’t realise and thus didn’t act on it for several hours.
https://en.wikipedia.org/wiki/Kursk_submarine_disaster