Looking like the perpetrator was a disaffected ex-JW member.
Yes, he left the JW about a year ago, reportedly not on good terms.
According to official sources, it was pure luck a police unit was close to the location at the time an emergency call came in, so it took the cops just four minutes to storm the building, preventing this psychopath to do even more harm. He had several more magazines with them and legally owned a gun. After police arrived, he escaped to the upper floor and committed suicide.
