I saw this link and didn't bother to check it, but I think you hit the jackpot: Palace of the Grand Master Explosion, in Rhodes On 4 April 1856, the Ottomans

I saw this link and didn't bother to check it, but I think you hit the jackpot: Palace of the Grand Master Explosion, in Rhodes On 4 April 1856, the Ottomans had storaged a large amount of gunpowder in the palace and the adjacent church, which were also full of people. In that time, it was considered that the ringing of bells could prevent the formation of storms. Unfortunately, a lightning hit the gunpowder, triggering a huge blast that killed 4,000 people. Thanks.