After the recent police shooting of a Black man in the US, hundreds of people have demonstrated in Philadelphia, with looting and violence breaking out in the second night of unrest.

On Twitter, the police department warned that "a large crowd" of about 1,000 individuals were looting businesses in the Castor and Aramingo area, advising citizens to "avoid the area."

It appeared that footage from a news helicopter showed people breaking into a Foot Locker store and looting another business.

In West Philadelphia, where another crowd of an estimated 1,000 people had gathered, an AFP reporter at another location saw police armed with batons clashing violently with several dozen protesters.

"The office of Pennsylvania Governor Tom Wolf announced the deployment to the city of several hundred National Guard troops" to safeguard the right to assemble and protest peacefully while keeping people safe.

The White House said in a statement released early on Wednesday that it was "ready, on request, to deploy any and all federal resources to end these riots."

Wave of demonstrations

A day after the death of 27-year-old Walter Wallace, whose family said he had mental health problems, fresh unrest ensued. Hundreds of protestors took to the streets on Monday night, with riot police pushing them back with shields and batons.

There is a lot of confusion, "said Ezra Alidow, a 25-year-old artist," about why the police shot the young man dead.

"All over America, it's happening. It's scary," he said. "These cops were undertrained."

During the first night of sporadic riots and looting in the city on Monday, more than 90 arrests were made, and 30 police officers were injured, including one whose leg was broken when a truck hit him.

"We anticipate the possibility of additional incidents of civil unrest today and this evening," Philadelphia Police Commissioner Danielle Outlaw told reporters.

As such, we will take further steps to ensure order, "she added, including improving police presence at key locations and deploying the looting response team."

Since the police murder of George Floyd in May in Minnesota, when an officer was filmed pressing his knee to handcuff Floyd's neck until he went limp, the US has seen a wave of protest and rioting.

Many of the protests have accused the police of racism and brutality, but in his election battle against Joe Biden, President Donald Trump has focused on the unrest to strengthen his claims to be the "law-and-order" candidate.

The White House declaration said the disturbances were "the most recent consequence of the war against the police by the Liberal Democrats."

"In a statement, the Democratic challenger and his running mate Kamala Harris said their" hearts are broken "for the family of Wallace.

But they also called on demonstrators to peacefully protest.

"They said," No amount of rage over the very real injustices in our society excuses violence.

Looting is not a protest, it is a crime. Biden and Harris added, "It draws attention away from the real tragedy of a life cut short."

Local media reported that on Monday afternoon, two officers shot Wallace at around 4 pm (2000 GMT) after he refused to drop the knife as his mother attempted to restrain him.

Wallace's phone video of the killing posted on social media showed his mother being pushed away and then walking towards the police.

Put down the knife, "shouted one of the officers in the video, panning off as the officers opened fire."

The family of the Philadelphia victim sought an ambulance, not the police.

According to their lawyer, the family of a Black man killed by Philadelphia police officers in a video shooting called for an ambulance to get him to help with a mental health crisis, not for police intervention.

The police said Walter Wallace Jr., 27, wielded a knife and ignored orders to drop the gun before shots were fired on Monday afternoon by officers. But on Tuesday night, his parents said that officers knew their son was in a mental health crisis because on Monday they had been to the family's house three times.

One time, Cathy Wallace, his mother, said, "They were standing there and laughing at us."

The attorney for the Wallace family, Shaka Johnson, said the wife of the man, Dominique Wallace, is pregnant and labor is scheduled to be induced on Wednesday. Johnson said Wallace had nine children, two of whom spoke briefly at a news conference late Tuesday, along with the mother and father of Walter Wallace.

The only tool you have to deal with when you come to a scene where someone is in a mental crisis is a gun ... Where are the right instruments for the task? Johnson said, arguing that police officers in Philadelphia are not properly trained to address mental health crises.

Johnson said 911 was called by Wallace's brother to request medical assistance and an ambulance.

'Why were they not using a Taser? According to the Philadelphia Inquirer, Wallace's father, also called Walter Wallace, said his son appeared to have been shot 10 times.

"Why didn't they use a Taser?" he was quoted as saying in the paper.

"He has mental problems. Why do you have to shoot him down?" he added, saying that he was on medication with his son. An investigation was launched by Outlaw, saying the video "raises many questions."

"While I was on stage this evening, I heard and felt the community 's anger," she said in a statement.

Wallace's shooting comes a week after an officer in Waukegan, north of Chicago, killed Marcellis Stinnette, a 19-year-old black man when he opened fire on his vehicle.

Also wounded was his 20-year-old partner, Tafara Williams.

"When will America end?" civil rights lawyer Ben Crump asked at Tuesday's press conference.

"Because of police brutality, excessive force, bias, systematic racism, deliberate indifference, how many more Blacks have to be killed?"