how should we act to school shootings?

This topic is a very hard topic to write about. if you don't know yesterday at a Florida school a student shot and killed seventeen people and injured countless others. This student is a serial killer, he's hurt so many people. What should we do? I'm a Christian and this is a very hard topic to discuss because I honestly wouldn't know what I'd do if (God forbid) if I was in that sort of situation. In the bible Jesus says many times to love one another as much I have loved you and to forgive others but, should we forgive people whom have committed these horrible acts? should we forgive serial killers and terrorist? this is something I struggle with because people have hurt me in my past nothing serious but, I have had people tell me to go do some physically impossible things and other things I won't say and I have forgiven them. I'm not bragging nor saying I'm such a great person and everyone should know it I'm only doing what I think is right and what Jesus has told me to do. But, what about the people whom have done worse and in this case shot and killed seventeen people and injured countless others should we forgive him. now I'm not saying me smack his wrist and send him on his way. no, what I'm saying is if the victims of these crimes are Christian should they have to forgive them? well this has happened before in the case of the green lake serial killer. Gary Leon  Ridgway was a serial killer who is believed to responsible for 90 deaths. this man was and is a serial killer and when he was arrested and in court the families of the victims where allowed to speak to him. a lot of families where telling to "go die" and to "rot in Hell" but, one man who's daughter had been murdered by this man had something to say. he told the man whom had murdered his daughter that he forgives him and that the pain he had caused him and his family was immense but he did have to do what he's Lord had asked of him. but he forgave the man and was even allowed to hug him. this is what Jesus did say but there are some verses in the old testament that do say that the person should be killed. but, it depends on the context. The bible does say that God has given governments a sword and that sword is mad to strike down it's enemies. this is not a topic that can be fixed with one answer but with many the solution is easy for some yet hard for many.