Obviously a lot of unanswered questions, but all the ones people actually are asking COULD have answers
1. Why was there live ammo on the set? Could be a mistake
2. Why was the gun handler unqualified? Maybe she was cheap compared to a real expert.
etc.
But there’s one question I haven’t seen raised anywhere: why was he firing the gun at a producer instead of another actor?
Even if the rounds were blank, why would you shoot blanks, except at another actor while you are filming a shooting scene?
John Schneider did a very good interview about gun safety on sets. Its on Youtube. Alec Baldwin disregarded just about every rule in the business according to Schneider.
So far a couple of crew on set have said that the director and/or cinematographer wanted another take on the scene Baldwin was in. Baldwin got pissed off, pointed what he thought was a prop gun at them, uttered profanities and fired.
So far on separate threads I've seen two versions of the same story and given Baldwin's well known volatility, it's entirely possible it happened that way.