Let's call the center row positions as 1 2 3 4 5 6 7 (creatures comes in the order of 4 - 2 - 6 - 3 - 5 - 1 - 7, IIRC).
If a creature in slot 4 is targeted, the damage will splash to 3 and 5, right? If 4 didn't die, but 3 and 5 died, where are the craters?