In the parking garage, the bad guy has a double barrel shotgun which by design can only hold 2 rounds. He fires once at the girl, then twice at Hooker, all without reloading.
The scene for the first shooting shows the "bad guy" loading his shotgun. The rounds he loads have already been fired, as noted by the dimpled primer.
When the killer returns to his apartment after murdering his latest victim, he picks up a newspaper that was on his table and the story of her death is already on the front page even though the crime just happened.
Top section of van blew off before the explosion.