Terrorism in the United States

The Bobby Eaton show.  I am glued to the news regarding the terrible attack by a 64-year old gunman on thousands of participants in a concert in Las Vegas, USA.  Las Vegas is a well-known vacation resort town with thousands of residents and tourists thronging the “Strip” until late at night on any given day.  But this night, Sunday night, ended in tragedy.  Armed with multiple automatic weapons and hundreds of bullets, he shot into the audience from his hotel, killing at least 59 people and wounding hundreds.  We are shocked at the depravity of it all and wonder who is this human being who would plan to murder so many people at once?  People he never met.  People who just wanted to enjoy a concert, to sing and clap and dance.  How does this happen?  What were his motivations?  Were there signs that pointed to this tragic outcome?