No. Clear reports were heard and described by several witnesses in multiple attacks.
1. Single round per attack
a. Could be fire discipline, esp. if this is a trained attacker or terrorist
b. Could mean sniper is using a turnbolt, either long arm or something like a Contender
c. The brass picked up with the Tarot card was the only one reported. Was it a plant?
2. If the sniper is using a semiauto, he has to be using a brass catcher, and the brass discovered with the Tarot card is his, that got away somehow? If he's using a turnbolt weapon, the brass is probably a plant from another type weapon in .223 cal. If he's using a semiauto with brass catcher, then he is exercising fire discipline, and the brass may be a plant anyway.
3. If the sniper is planting misleading evidence, then confusion is a major goal, either to help him evade/escape, or because he's a terrorist.
4. If the sniper is using a semiauto like a CAR-15, then he is exercising fire discipline. Does that make him a trained terrorist?
5. Either way, he's a fanatic, taking huge chances.
That's as far as I want to go right now.
By the way, using two vehicles doesn't make sense. Why a two-man team? They couldn't communicate without being compromised by NSA, law enforcement, or someone else.
Diversion. Shot fired and one vehicle takes off. Fast enough to be noticed, by witnesses, this would give the shooter a little cover for getting out in the opposite direction/alternate route?