Why Mass Murder in Colorado’s Gay Nightclub?

Another terrible mass murder has been committed in Colorado Springs when a 22-year-old man went into a gay nightclub with a long gun and killed five people.  How could this happen? What could have been done to prevent this heinous crime? How can we make sure those mass murders won’t happen again? What do we know about the childhood of the murderer? And could our society’s approach towards violence have any role to play in this? What does GOD tell us what the only true solution is?