Nearly 40 cities in the U.S. have imposed curfews as protests sweep across the country. Nearly every major American city has seen large demonstrations, some turning violent. Protesters are calling for an end to police brutality and racial discrimination after the death of an unarmed black man, George Floyd. Now the anger has spread far beyond Minnesota where clashes have broken out between police and protesters. Five thousand National Guard troops have been activated in 15 states and the District of Columbia. Over 1,000 people have been arrested in 16 cities since Thursday.