As city officials on Sunday sought to explain how peaceful protests over police brutality a day earlier had morphed into looting and chaos in Center City, Philadelphia Police Commissioner Danielle Outlaw acknowledged that the department’s plan for responding to the situation “did not happen as quickly as I would’ve liked it to occur.”

But even as Mayor Jim Kenney’s administration took steps designed to correct for that Sunday, the unrest spread into outlying city neighborhoods, prompting additional questions about whether police had adequately prepared for the mayhem that also gripped other major U.S. cities, and how long the volatility might linger.

Some within the department grumbled privately that officials were slow in preparing for protests that were not unexpected, leaving the city under-protected and under-resourced as pent-up frustration and anger swelled over last week’s killing of George Floyd while in the custody of Minneapolis police.

John McNesby, president of the Fraternal Order of Police Lodge 5, which represents the Philadelphia rank and file, said in an interview Sunday that he didn’t believe enough officers had been deployed before the otherwise peaceful protests gave way to violence. And the union he leads took an unusually public swipe at the department, tweeting: “Does [Internal Affairs] handle complaints for lack of strategic planning, leadership and basic understanding of crowd control? Asking for a few thousand friends.”

At a Sunday evening news conference, Kenney and Managing Director Brian Abernathy said that the department had faced an unprecedented deployment challenge — one occurring in the midst of a pandemic — and that delays in responding to scenes were more an issue of staffing numbers than a lack of will.

On Saturday, for example, authorities were largely tied up responding to vandalism, arson, and some 3,000 to 4,000 demonstrators at City Hall as looters began ransacking stores in Center City’s commercial corridors, Abernathy said.

And the mayor said that although officers on Sunday were able to respond much more quickly to trouble spots in Kensington, Port Richmond, and West Philadelphia, it remained difficult to balance how and where to properly deploy police — particularly as other emergencies, including shootings, continued across the city. At least 13 people were shot across the city on Sunday, including a 12-year-old boy struck twice in the arm during a quadruple shooting in Kensington.

“It’s difficult to take those officers at 52nd and Chestnut who are having cars set on fire, dealing with looters at a corner store … and then divert those officers to another location,” Kenney said, referring to perhaps the most volatile hot spot. “We’d be overrun in both places.”

By 9 p.m. Sunday, at least 269 people had been arrested over the two days of unrest, officials said. The vast majority were issued tickets for violating curfew or failing to dismiss. Four people were charged with assaulting police, 66 others with looting.

No names had been released as of Sunday evening, and city officials differed in their opinions as to who the offenders were. Kenney and Outlaw blamed outside agitators.

“We’re not tearing up our own neighborhoods,” the police commissioner said. “It’s the people who are coming in from elsewhere.”

But District Attorney Larry Krasner and defense lawyers said many of those arrested Saturday were from Philadelphia. Deputy Police Commissioner Christine Coulter said that much of Sunday’s sustained unrest was being caused by “people working to hurt their own neighborhoods.”

During a media briefing earlier Sunday, Outlaw was asked whether the department had followed steps used in the past to respond to large-scale demonstrations, such as extending officers’ shifts, placing some officers along business corridors for protection, and having cops in the crowd. She said that such a strategy “did come into place,” but acknowledged that it was slow to develop.

It wasn’t until after the city declared an 8 p.m. curfew Saturday that police were able to get a better handle on the situation, she said.

“We did not sit on our hands,” said Outlaw, in her third month on the job after serving as chief in Portland, Ore. “The reality is that things will pop up and flare up where we do not have a presence or we do not have enough resources at that time to take action safely.”

Abernathy said that if police officers trying to protect City Hall on Saturday night had left to head toward the looting, it could have been dangerous given the number of people and volatility of the situation they were trying to contain.

“By no means did officers lay down or allow illegal activity to happen" in the shopping district, Abernathy said. "But I’m not going to allow our officers … to put themselves at risk when they’re outnumbered 10-1.”

Even as he was speaking, police were firing tear gas at people in West Philadelphia, one of several neighborhoods where additional unrest boiled over in the form of looting, vandalism, and police cars being burned.

Standing at a McDonald’s with smashed windows at 52nd and Chestnut, a 36-year-old man who did not give his name watched as protesters faced off against a line of police.

“I don’t agree with the stealing, but people just want to be heard,” he said. “Stop treating us like we’re animals. …. We’re fed up with being attacked and hurt and nothing done about it."

Center City streets, meanwhile, stood largely empty Sunday. A huge armada of officers stood guard in front of the statue of Frank Rizzo, the former mayor and police commissioner — which had been the target of vandals Saturday — and officers in riot gear guarded Police Headquarters as a crowd of peaceful demonstrators assembled outside

City officials urged demonstrators to go home, and said hundreds of Pennsylvania national guardsmen would be moved into Philadelphia on Sunday evening to bolster police deployment as unrest continued.

“We certainly haven’t and we won’t abandon any of our commercial corridors,” Abernathy said.

Staff writers Allison Steele, Maddie Hanna, and Aubrey Whelan contributed to this article.