How to make an NPC shoot at you after you shoot at it?

To further explain, I am making a game where you are supposed to eliminate the enemy NPC. But to make it fun I want the NPC's to shoot back only when you shoot at them. I already made the NPC and the gun it uses. I am also willing to give Robux for a quality script. Here's my game if you want to further understand the concept:https://www.roblox.com/games/1804310321/PROJECT-SPY-READ-DESC