Each Building Part has an attached script "InstantiateOnDestroy.cs" in the children mesh to instantiate its own fractured model upon destruction, resulting in a more realistic effect.
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The models are basic models fractured with Fracture Tools addon in Blender.
Colliders and rigidbody were added on each fragements to simulate the realistic destruction.
You can also use tools like RayFire to achieve similar effects on your own models.