Kill an ennemy open the way

Hey guys , i have little problem. I have 3 ennemies on my level , and this is what i want : when one of them see the player , the others start to attack too and two doors block the ways . Thanks ( sorry my english is not perfect i am not english )

Screen :

There are so many ways to do this, I can’t decide which one to choose. I suppose I would prefer event dispatchers

yes , but event dispatchers work with the Level BP , and i don’t really now how to do this … so if you can help me.

Ok , so i watch a video , and i know a little how work event dispatchers. So i had done this : When an ennemy see the player he call an event “Alerted” , and when he die , he call again this event.
In the level BP have bind this event “Alerted” to an other event. So with a flip flop , when the ennemy see the player the doors rise , and when he die , the doors go down , but how do this when there is more than ennemy ?

Ok , I finally found a solution , thanks !!!