Hundreds of protesters in Philadelphia have 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.
Wallace had bipolar disorder, and his wife told officers this before they shot him, a lawyer representing his family said.
Philadelphia also saw large protests earlier this year over police brutality and racism following the death of George Floyd in Minnesota.
What's the situation in Philadelphia?
On Tuesday night (US time), the marches 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.
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 set up barricades on Tuesday.
Residents found pharmacies shuttered and were unable to get medicine, according to CBS News.
What have city officials been saying?
Mayor Jim Kenney, a Democrat, has said the video of Monday's fatal police shooting "presents difficult questions that must be answered".
The mayor said he was looking forward "to a speedy and transparent resolution for the sake of Mr Wallace, his family, the officers, and for Philadelphia".
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. "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.
What do we know about the shooting?
Police said the shooting happened about 4pm (local time) on Monday, when two officers responded to a report of a man with a weapon in the neighbourhood of Cobbs Creek in West Philadelphia.
Police spokeswoman Tanya Little told AP news agency that a man, later identified as Wallace, was holding a knife when the officers approached, and instead of following orders to drop the weapon "advanced towards them".
Both officers fired "several times", hitting Wallace in the shoulder and chest.
One of the officers drove him to a hospital, where he was pronounced dead, Little said.
Footage shared on social media shows two officers pointing their guns at Wallace as he walks towards them. The officers back away from him and shout at him to put the knife down.
Shots are then fired and Wallace is seen lying on the street.
Wallace's father told the Philadelphia Inquirer that his son had mental health issues and was on medication.
"Why didn't they use a taser?" he asked.
Meanwhile, Wallace's family lawyer said that they had called for an ambulance - not police - to help deal with Walter Wallace's mental issues.
Instead, two police officers arrived, lawyer Shaka Johnson was quoted as saying by the Inquirer. Wallace's pregnant wife told them her husband had bipolar disorder and was in crisis.
Reacting to the shooting, Democratic presidential candidate Joe Biden and his running mate Kamala Harris said in a statement: "Our hearts are broken for the family of Walter Wallace Jr., and for all those suffering the emotional weight of learning about another Black life in America lost. We cannot accept that in this country a mental health crisis ends in death."