Originally, the police had said to be on the look out for two men based on witnesses. Also, I think they thought it was a shoot and run, which led many to believe that the shooter fired and there was a driver ready to go.
If the reports are true that there was grass pressed down where the shooter had lined up the shot, then I think it is very possible the shooter is working alone. If he moved that far away from the vehicle then the motor wouldn't have to be running. On the other hand, I don't think the card necessarily precludes a second individual being involved. Taking the shot would be a personal experience and the shooter still might use the singular in a note. Finally, if the reports of the Tarot card are accurate, I think terrorism is much less likely.
I will try to be tuning in through out the day as well.