All this info is located in other plugins (the very reason why this is open source community). I'll sum it up for you:
1) Hook fire in the hole sound.
2) Get grenade, then by model figure out what kind of grenade it is.
3) The owner of that grenade is obviously the thrower.
4) Hook a flash event, these are the "victims" of the nade. Somehow get what grenade fired the message.