ardvarcus

The initial blast that started the fire may have been a bomb or rocket from an Israeli source or agent. I don't believe the larger second blast was from a bomb. It was caused by barrels of fertilizer igniting. Now, ordinarily they don't ignite, so it's very possible this was a weapons-making factory run by Islamic terrorists, and the barrels of fertilizer had been treated with fuel oil, which turns it into an explosive that is still hard to set off, but not impossible to set off.

This would explain the sparks of light seen in the fire -- small arms ammunition or small explosive devices going off. It may have been fireworks if this was a fireworks factory, but Israel doesn't bomb fireworks factories, so it was probably ammunition of various kinds.

I suspect that the big blast caught Israel as much by surprise as it did the people near the warehouse. They would not have wanted to set off such a huge explosion in a densely populated part of the city. It was a mistake, even though some Isreali Jews are celebrating it.