When the people around realized that Jake had been attacked all of a sudden, all of them froze. Then, by the time that they began reacting, Jake had already been long dead.
With Jake already out of the picture, the other monsters that were attacking finally got an advantage. Since there was nobody that was capable of dealing much damage to them, the large swarm of sea monsters suddenly managed to reach the people at the middle floors of the building.
Some of them tried rushing towards the top floor of the building, but, they were not capable of doing that before they were killed off. And in no time at all, the entire mutant warrior association had already been cleared out.
