Specific Enemy Detection

In my game I have multiples of one enemy type, but when one is destroyed all enemies of that type is destroyed. I know that is possible but can not think of the easiest way to do so.

https://flowlab.io/game/view/1582540 If you would like to take a peek (Its a sloppy mess beware)

Here is a thought: Whenever you attack a enemy, send a message to previous object, then have a mailbox on the enemy. then tell it to destroy.

Thank you I figured it out. The reason that all enemies of that type was dying was due to me using global blocks to store HP numbers.