Looking back I can see I was very vague with the description.

Essentially what happened is that D'Angelo saw his mark, you yelled and startled everyone. So D'Angelo threw out that smoke bomb as a distraction and climbed the roof. He saw your cat-demon a little ways away, but decided to finish his job and shot his original target through the thinning smoke before returning his attention back to you.

I can make it more clear in the post if you'd like.