Hundreds of protesters in Philadelphia marched through the city for a second night, demanding racial justice after police fatally shot a black man.
The family of Walter Wallace, 27, say he was suffering a mental health crisis when officers opened fire on him.
Police say they shot him because he wouldn’t drop a knife he was holding.
Police reinforcements as well as the National Guard have been deployed. Officials say 30 officers were hurt during the first night of clashes.
The city’s police have also accused protesters of looting and ransacking businesses during the unrest.
Mr Wallace had bipolar disorder, and his wife told officers this before they shot him, a lawyer representing his family said.
Marches on on Tuesday night began peacefully, but became more confrontational as the evening drew on.
Officers in riot gear arrived in squad cars, on bicycles and on buses, and used their bikes to shove protesters back from barricade lines.
Police also warned residents to stay away from the riverfront Port Richmond district as widespread looting occurred.
The Philadelphia Office of Emergency Management advised residents across a swathe of the city to stay indoors because of “widespread demonstrations that have turned violent”.
According to the Philadelphia Inquirer, protesters tried to erect makeshift barricades using bins. Police used pepper spray and batons after saying they were attacked by demonstrators.
Shops around the city had closed early and constructed barricades on Tuesday.
Philadelphia Police Commissioner Danielle Outlaw said she had visited the scene and felt the “anger of the community”.
“We anticipate the chance of additional incidents of civil unrest,” she said at a news conference earlier on Tuesday. “And as such, we will be taking additional steps to ensure order. We will increase our officer presence around the city at key locations.”
Large protests broke out in Philadelphia earlier this year following the police killing of George Floyd in Minneapolis, Minnesota. Footage showed white police officer Derek Chauvin kneeling on the black man’s neck, while he repeatedly said he was unable to breathe.
Floyd’s death sparked protests around the world against racism and police brutality.