President Donald Trump has threatened to send in the military to quell growing civil unrest in the US over the death of a black man in police custody.
He said if cities and states failed to control the protests and “defend their residents” he would deploy the army and “quickly solve the problem for them”.
Protests over the death of George Floyd have escalated over the past week.
Four police meanwhile have been shot and injured in Missouri, and two people reported killed amid unrest in Chicago.
The circumstances of both incidents are unclear.
Meanwhile, dozens of major cities imposed overnight curfews on Monday night. New York City is under lockdown until 05:00 (09:00 GMT) on Tuesday and Washington DC has extended its curfew for another two nights.
In New York, the iconic department store Macy’s was broken into and a Nike store was looted, while other shop fronts and bank windows were smashed. Several people were arrested. Curfew will begin in the city at 20:00 (midnight GMT).
The protests began after a video showed Mr Floyd, 46, being arrested in Minneapolis on 25 May and a white police officer continuing to kneel on his neck even after he pleaded that he could not breathe.
The officer, Derek Chauvin, has been charged with third-degree murder and will appear in court next week. Three other police officers have been fired.
The Floyd case has reignited deep-seated anger over police killings of black Americans and racism. It follows the high-profile cases of Michael Brown in Ferguson, Eric Garner in New York and others that have driven the Black Lives Matter movement.