The video above is an alarming example of what can happen with a lack of regulation and safety procedures. A crew of Baltimore city contractors was demolishing an old row house with a large crack in the wall. Everything seemed to go well at first until the neighboring building, which was not supposed to be demolished, came crashing down too.
http://gizmodo.com/watch-a-mortified-demolition-crew-accidentally-tear-dow-1795462647