Oct. 29 (UPI) -- Philadelphia was under curfew overnight after two nights of unrest that opposed the police killing of Walter Wallace Jr., a mentally ill Black man, on the city's west side this week.
Philadelphia Mayor Jim Kenney ordered the curfew and President Donald Trump has threatened to send in federal forces "if requested."
The unrest led to clashes with police and dozens of arrests. Officials said there has been some looting.
Wallace, 27, was shot Monday after officers said he brandished a knife and refused orders to drop the weapon. Video of the shooting led to protests and outcry over police tactics that were used to control a man with a documented mental illness.
Kenney and Philadelphia Police Commissioner Danielle Outlaw said they want to preserve the right for demonstrators to protest, but promised to take action against looters and those who instigate violence.
"Let me be perfectly clear: This behavior is not acceptable under any circumstance, nor will it ever be tolerated," Outlaw said.
Kenney said National Guard troops will arrive on Friday to help police.
Police made more than 80 arrests Tuesday and Wednesday and nearly two dozen police officers were injured in clashes. Since Wallace's death on Monday, police said they have made almost 200 arrests.
Wallace's family has asked for calm.
"Have respect for my family and my son and stop this violence and chaos that's going on in the city," Walter Wallace Sr. said.
Mother Cathy Wallace, who was present at Monday's shooting, said she pleaded with officers not to shoot her son. Family attorney Shaka Johnson said police had been called at least three times to the home, but a final 911 call asked for medics.
"[Wallace] was suffering," Johnson said. "He was on doctor's care. He was on a regiment of lithium, etc., and the police were here earlier that day."
John McNesby, president of the Fraternal Order of Police Lodge 5, called on Outlaw to release more information about the shooting.
Trump's campaign blamed the shooting on"liberal Democrats" and said the president is monitoring the situation.
Democratic presidential nominee Joe Biden echoed the call from Wallace's father for calm and condemned the looting.