At Astor Place and Broadway the parade stops as the police arrest several individuals who according to witnesses would not remove the masks that they were wearing . Wearing a mask at a political demonstration is , under a law that has been on the books since the 19th century , a crime and is a behavior that is rarely tolerated by NYPD . The marchers were not all that well behaved here as they spread across Broadway and it seemed to some witnesses that there might be a small riot .
After a several minute halt to the downtown progress of the marchers the police finally restore order and the parade moves on .