Demonstration against police killings of black men turns violent in Boston.

Tens of thousands of people of all races march from Nubian Square to the State House. The demonstration was organized on Twitter by three college students. Afterwards, hundreds of people riot, set fires and loot stores in Downtown Crossing and the Back Bay. Nine police officers and 18 others are hospitalized, 53 people are arrested (27 from Boston), and the National Guard is called in to restore order.