Oh yes. Essentially you're within your legal rights to be in your own store during a riot, and while there are legitimately allowed to fear for not only your property but also your life, and are within your rights to shoot anyone coming through a locked door or window. For a historical example:
For the record Korean owned businesses made up about 45% of the damage in the 92 riots, despite the protection. One iconic image showed Korean business owners firing pistols into a roving looter mob, framing the race war in an image. It also spawned this hilarious meme:
http://static.fjcdn.com/pictures/Baltimore+riot+photos+part+2_e96f8c_5529845.jpgFerguson saw similar responses from business owners after the first night of destruction.
That's pretty funny.