Note that Minneapolis state police have claimed that the reporters were released from jail the following morning after confirming themselves as media, which CNN responded by saying they had identified themselves before their arrest and it was only through the Goverers interference that their reporters were released the following morning.
I mean, it happened live on air, they were clearly identified as CNN and willing to comply with police orders - making the police's claim laughable. I wonder what those officers were thinking, arresting a reporter on live camera.
Speaking as someone who's been to a lot of protests, ranging from "peaceful as a baby" to "as street medics we treated 1/3-1/2 of the protestors"... the same thing cops are always thinking. As an institution, they don't like the press, oversight, or public scrutiny of their actions. They react the same way to people with press credentials for less prominent organizations, and to regular humans with phone cameras who have just as much a right to record video, the same way all the time.