How To Play A Different Animation When Bullet Contacts With A Certain Limb?

Hello, ok so i have a character set up. I have bullets and enemies. I have different death animations set up depeding on where the bullet hits an enemy. For example if a bullet hits an enemy the head, the head explodes and if a bullet hits an enemy on the arm, the arm is blown off etc. The animations and models are done in Blender. So my question is how would i code this, for example, if bullet collides with head then play animation1. I understand the logic of this but i don't understand the code in C#. Thanks in advance if anyone can help.