As the streets exterior his residence echoed with pops, Darryl Steplight thought it was fireworks on the eve of the Fourth of July. He rapidly realized in any other case. A person in physique armor, and carrying an AR-15-style rifle, had opened fireplace at random within the neighborhood, killing 5 and wounding two, together with a 2-year-old.

The man who was arrested and charged with finishing up the rampage was Kimbrady Carriker, whom Mr. Steplight had met simply final week.

The encounter was unremarkable, Mr. Steplight mentioned, aside from one curious element: Mr. Carriker, who was sporting a inexperienced military-style vest, had launched himself as a “town watchman.”

On Wednesday, two days after the mass taking pictures in southwest Philadelphia, town was attempting to know what had touched off such an inexplicable outburst of violence. In the morning, Mr. Carriker, 40, was arraigned, showing by video in a white jumpsuit and providing terse responses as a Justice of the Peace learn out the costs, together with homicide, tried homicide and reckless endangerment. He was ordered held with out bond.

At a news convention within the afternoon, prosecutors mentioned that individuals who lived with Mr. Carriker had instructed investigators that he had been “exhibiting abnormal behavior” and “getting more and more agitated” in latest days, even sporting his bulletproof vest round the home. A search of his residence, mentioned Robert Wainwright, an assistant district lawyer, turned up a will that Mr. Carriker had written, dated June 23. Mr. Wainwright didn’t say what was within the will.

The authorities mentioned that when Mr. Carriker was arrested he had an AR-15-style rifle and a so-called ghost gun, produced from untraceable components, although investigators had but to find out how he obtained the firearms.

Prosecutors mentioned the ghost gun was not fired through the taking pictures, and {that a} handgun and ammunition had been discovered through the search of Mr. Carriker’s residence. Mr. Carriker didn’t have a license to own weapons, prosecutors mentioned.

Mr. Wainwright mentioned at the least one of many seven individuals who shared a home with Mr. Carriker had acknowledged that he was turning into extra disturbed. But one other prosecutor, Joanne Pescatore, mentioned “their way of dealing with it was just to avoid it and not interfere with him.”

Pennsylvania doesn’t have a “red flag” regulation, which permits households or regulation enforcement to hunt a courtroom order quickly seizing weapons from individuals deemed a menace to themselves or others. But officers inspired individuals to report troubling habits anyway, suggesting that Mr. Carriker may need gotten assist had the authorities recognized of his habits. After a 2004 misdemeanor conviction for carrying a gun with out a license, Mr. Carriker had apparently spent his life largely off the radar of native regulation enforcement.

He was, nonetheless, a well-known determine to his neighbors on the block of two-story rowhouses the place he had been dwelling. They remembered him as pleasant and at instances useful. “He never gave us a problem, he was always a nice guy,” mentioned Bernard Mason, 53, who lives throughout the road. “We saw him a couple of times in full heels and a dress and didn’t think nothing of it, that’s his thing.”

Mr. Carriker appeared in ladies’s clothes in some photographs on his Facebook web page, probably contributing to confusion over his gender identification within the preliminary hours after his arrest. The district lawyer’s workplace mentioned on Wednesday that they’d seen no data to counsel that he considers himself something however male.

It was on social media that Mr. Carriker’s frame of mind might have been most seen to individuals exterior his residence. His Facebook web page suggests a libertarian-shaded politics, with memes disparaging President Biden alongside posts in help of the Black Lives Matter motion, and thru all of it help for unrestricted gun rights.

In the times main as much as the mass taking pictures, his Facebook exercise — posts about being adopted by evil spirits, alongside articles about efforts to handle gun violence in Philadelphia — might have mirrored the agitation that the prosecutors described.

“But we prayed to our God and posted a guard day and night to meet this threat,” learn a put up from final Saturday, two days earlier than the taking pictures. It was adopted by an excerpt from the ebook of Isaiah: “To save you, I will send an army against Babylon,” learn one verse. “I will break down the city gates; and the shouts of her people will turn into crying.”

Jon Hurdle contributed reporting. Kirsten Noyes contributed analysis.