The police in Standing Rock perfectly represent how our "boys in blue" really act when they thing they're not being watched. They don't see protestors as a threat, they just are furious that people are daring to resist their authority. They're the real "thugs" that conservative media is always screaming about.
Anyone who doesn’t trust police is going to assume that they shot the woman or hit her with some type of strange device. We cannot draw that conclusion if we have no visual proof or testimony from the woman that the police did it. Furthermore, protesting is risky business. People must understand that they are signing up for possible dangers if they decide to protest. That danger could come from any human being.
According to witnesses the woman, who was protesting at the time, was struck on the arm by a police weapon. The woman herself claims she was struck by a police concussion grenade. The police deny this and claim the protestors might have been planning to cause explosions, as they found some propane tanks on the site. However, no one has been arrested for making explosives and the police were seen to use tear gas and sponge bullets against the group.
The police have been more than patient with the people trying to shut down business. The people building the pipeline have the right to be there. The people protesting are imposing anarchy. At some point, the police have to use force in order to clear the area so that the business owners can do their lawful work.