> The Hindenburg catastrophe, May 6, 1937
https://en.wikipedia.org/wiki/Hindenburg_disaster says 36 deaths.
I was going to complain about the missing Beirut 2020 (216 deaths), but the article is from 2013.
From https://en.wikipedia.org/wiki/List_of_explosions to get in the infamous top 25, it's necessary more than 300 deaths, but that list don't include explosions during war and similar events.