Hopefully we're not talking America's most Stupid Criminal here. Also the question is kinda hard to follow. Hoping that the previous is not the case, the it most likely is:
4
Proof:
1. No smart/scrambling shoppers would grab a gun and run out. Rules out 1.
2. Clerk gave him money. That rules out 2.
3. He's close enough to get blood on his hand and sleeves at least. This rules out 3.
4. Is the only person that cannot have the qualities of the robber, because even if he did wear it he would've taken it off immediately upon exiting, else be a dead giveaway.
5. He was arrested, so crying and upset is possible. Ruling out 5.
6. He could have been wearing gloves, since it does not mention him dropping and leaving the gun. Ruling out 6.