Edit: Ouch, looks like quite a few people here do. Do y'all really think that's the best way to effect social and political change? A minority of Americans screaming louder and using terrorism to vent their spleens won't solve the issue. In a democracy, everyone must focus on getting more people to vote for different policies to effect change.
In this particular case, I do find some of the violence justified, and I think it has more effect than a simple non-violent protest would. We get to see exactly how police respond when a few thousand dollars worth of property is being damaged versus when they have someone's life in their hands. The police are digging themselves into a hole here, and it's glorious.
That said, we aren't at the point where violence against people is a legitimate form of protest. In self defense, sure, but protesters should not, at this point, be attacking people. Burn down all the Targets, police stations, and cop cars you want. Let it be the cops who do all the violence against people. That's what's actually going to get peoples' attention.
I'm trying to be charitable here, so I will ask you to reflect on the reasons why you think protecting replaceable (or even irreplaceable) property is worth extinguishing a human life.
In light of your magnanimous question (inquiring after the views of another is called conversation, not charity), here's my rationale as to why one is justified in using lethal force to defend property.
Let's take an extreme case: Say I'm an immigrant from a third-world nation who arrives in America at a young age. I spend my life working to build a successful small business. I pour my blood, sweat, and tears into it. Now, someone comes along, full of "justified anger" and ready to burn it down. By doing this, he is destroying a huge portion of my life. While this is less severe than murder, it's on the same spectrum of evil; one is destroying another's entire life, the other, only part of another's life. Therefore, a man is justified in any amount of force necessary to protect his property.
I'm aware this isn't a common way to view, but I'm happy to answer more questions and defend it further. I don't believe life has any absolute importance over property because property represents a part of another life. While a person represents more life than a thing in most cases, a thief or arsonist forfeits his rights by committing crimes against another.
[0]: https://statutes.capitol.texas.gov/SOTWDocs/PE/htm/PE.9.htm
[1]: https://scholar.google.com/scholar_case?case=316114562717856...