3 male passengers then get out and start stabbing / shooting people according to early reports.
But it could have been anyone for any reason, who knows, possibly Jehovahs Witnesses or Amish.
Maybe we'll never know the reason but I'm sure there will be people praying for those involved and hashtags.
Thus solving the problem once and for all.
Just "Life in a big city" according to the Muslim Mayor of London, Sadiq Khan.