ground zero like everywhere else but they were left behind. If they were all turned to zombies then the area would have no bodies. Also for zombies as a whole to fear the haze they might have all tried to go in to ground zero.
Just a theory, but everyone wants to know what is at ground zero, even Pinstripe. Maybe Pinstripe ordered zombies to go into ground zero but they died. Skittles mentioned to Angel and Kalani that he didn't think there were any more Jumper zombies around. Maybe Skittles saw the dead Jumpers around ground zero or saw Pinstripe ordering them leaping into ground zero and dieing.