Officials in the US city of Philadelphia announced a curfew Wednesday following two nights of unrest over the latest police killing of a Black man.

The citywide order will last from 9:00 pm to 06:00 am (0100 to 1000 GMT Thursday), according to a statement on the city government's website.

A demonstrator, wearing a protective face mask, holds a placard reading "WALTER WALLACE JR." during a protest near the location where Walter Wallace, Jr. was killed by two police officers on October 27, 2020 in Philadelphia, Pennsylvania
A demonstrator, wearing a protective face mask, holds a placard reading "WALTER WALLACE JR." during a protest near the location where Walter Wallace, Jr. was killed by two police officers on October 27, 2020 in Philadelphia, Pennsylvania GETTY IMAGES NORTH AMERICA / Mark Makela

Thousands of people have taken to Philadelphia's streets, with looting and violence breaking out, after police on Monday shot dead 27-year-old Walter Wallace, who was carrying a knife.

His family said he suffered from mental health issues and asked why officers did not taser him instead.

Wallace's death and the subsequent demonstrations have also revived a political clash between Republicans and Democrats less than a week before the election.

Protesters march, clash with police and set fires in West Philadelphia during a second night of demonstrations following the police killing of Walter Wallace, a 27-year-old Black man.
Protesters march, clash with police and set fires in West Philadelphia during a second night of demonstrations following the police killing of Walter Wallace, a 27-year-old Black man. AFPTV / Eleonore SENS

"It's a terrible thing, what I am witnessing is terrible and frankly that the mayor or whoever it is that's allowing people to riot and loot and not stop them is also just a horrible thing," President Donald Trump told reporters.

The US has seen a wave of protests and rioting since the police killing of George Floyd in May in Minnesota, when an officer was filmed pressing his knee to handcuffed Floyd's neck until he went limp.

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

Demonstrators gather in protest near the location where Walter Wallace, Jr. was killed by two police officers on October 27, 2020 in Philadelphia, Pennsylvania
Demonstrators gather in protest near the location where Walter Wallace, Jr. was killed by two police officers on October 27, 2020 in Philadelphia, Pennsylvania GETTY IMAGES NORTH AMERICA / Mark Makela

On Tuesday, the Democratic challenger and his running mate Kamala Harris said in a statement that their "hearts are broken" for Wallace's family.

But they also called on demonstrators to protest peacefully.

"No amount of anger at the very real injustices in our society excuses violence," they said.

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

Two officers shot Wallace around 4:00 pm (2000 GMT) on Monday afternoon after he refused to drop the knife as his mother tried to restrain him.

Phone video of the killing posted on social media showed Wallace push his mother away and then walk towards the police.

"Put the knife down," one of the officers shouted in the video, which panned away as officers opened fire.

Philadelphia's police commissioner has launched an investigation into the shooting.

Joe biden Donald trump