I've been working on a significant residential remodel where the main level floor is post tension slab with traditional frame construction and the lower level is all concrete.

Between electrical, plumbing & HVAC there have been several hundred cores drilled ranging from 2"-16" in diameter.

They found where a core was drilled through the post tension floor for a drain back during original construction and one of the cables was hit.  Didn't cause catastrophic damage, but did blow out some of the surrounding concrete when it gave way.

I've heard bad stories about cut cables doing lots of damage, but I expect this is on larger structures like multi-story commercial buildings, bridges, etc.

Here's a couple photos... you can see the cut cable splayed out on the right side.