One off? Probably. You have several hundred people doing this? Not likely. The first-hand optics would shake even the police. They can shoot a person. They can't open fire on people. Not in the US. Not yet, at least.
Every time I try to look this up a get a variety of different answers. It seems like a lot of different protests using similar means.
The two most common that seem to pop up are:
Environmental protection laws. Farmers want to continue to burn fossil fuels, using pesticides, and dumping artificial fertilizers into the ground.
Economic protection from foreigners. I found at least one case where a McDonald's was the target because they allegedly were serving foreign-sourced beef