Protesters are expected to gather in Washington for a huge demonstration on Saturday, its police chief said, as U.S. street marches over the killing of a black man in custody enter a 12th day and authorities move to rein in policing tactics…

“We have a lot of public, open source information to suggest that the event on this upcoming Saturday may be one of the largest we’ve ever had in the city,” Washington DC Police Chief Peter Newsham told local media, adding that much of the city center would be closed to traffic from early in the day.

Newsham did not give a crowd estimate. Local media has predicted tens of thousands of attendees.