You’re right. 19 children died in the OKC bombing, no gun involved. CT has among the toughest gun control laws in the country. There is already a federal law prohibiting firearms of any kind in school buildings. None of that was a deterrent in this case.
He could have done it any number of ways besides a gun.
Had he gone in there with a machete those teachers weren't prepared to take him on.
Any way he chose to do it, nobody was prepared to stop him and he knew it.