Curfews have been imposed in multiple cities in the US, after unrest and protests have spread across the country over the death of an unarmed black man, George Floyd, in police custody.
Most of the protests began peacefully - and several stayed peaceful. But in a large number of cases, demonstrators clashed with police, set police cars on fire, vandalised property or looted shops. The National Guard has activated 5,000 of its personnel across 15 states and Washington DC.
Experts have also drawn parallels with the 2011 England riots - when a peaceful protest over a man who was shot dead by police turned into four days of unrest, with widespread looting and buildings set alight.