Russell was trying to hand out fliers to IRS employees, and then to the feds that came up to stop him. They told him he couldn't hand out fliers on postal property (I think the IRS office was in the same building as the post office). At some point after being told not to go in, he turned and began to walk up the steps. The feds arrested him. Apparently he was released and then went back and handed out fliers again!
Details are on this thread.