Right at that time two detectives disregarding the rules drove up close to the building and got out without getting their vests or rifles before getting into the active zone.
The shooter saw them and a gunfight ensued with the detectives firing their pistols, and injured the shooter with one round. The shooter sat down on the floor, put his gun to his head and killed himself.
The Army vet hero, Chris Mintz, survived and fully recovered. Physically that is. Emotionally I'm not sure. I could only find an article a year after the shooting, and it said he visits the school often and thinks about his friends (10 of them) that died.
I couldn't find anything more about him in more recent years. I hope he is doing well.
Oh - the shooter killed himself 8 minutes after the first 9-11 call was made. The two detectives (one car) were nearby. As they were driving in they figured they would be the first to arrive and they both agreed they were going to forego the SOP and they would just charge in.