Your event #4 is triggered on every tick. You can't use "Trigger once" here because you are dealing with multiple instances of pedestrians.
So you need to add another condition "Animation Dead is not playing", or change your event like this:
...Pedestrians set HP=-999
...Pedestrians set Animation to "Dead"
...Pedestrians set bullet speed to 0
...Pedestrians spawn BloodPool
Alternatively, you can simply move all these actions to event #3.