Environment Destruction

I am very sorry for being so broad, but could someone point me in the right direction, i need to accomplish destructible environments like in this video: http://www.youtube.com/watch?v=cfrL81qtbrk for an fps game i am making, if someone could help me that would be appreciated greatly!

 

Wow! It's really cool! I think it will be very difficult to achieve the same qualty of destruction. Usually uses easier technique - pre-modelled and animation of destruction, and all destruction looks same. But in this video it looks like objects destroying programatically at runtime. So, I think the first step is a changing the object's mesh, but I don't know how to close "holes".
In any case there are a lot of work reseach.

 

you could always ask them how they went about it...

http://forum.unity3d.com/threads/96339-DLG-No-Heroes-A-realistic-multiplayer-FPS/