A child is shot in Philadelphia every 3.7 days.

Shot while walking home from school, as 10-year-old Sameje O’Branty was last month in Frankford.

Shot while at home, as 2-year-old Nikolette Rivera was — in her mother’s arms — just a few weeks before that.

Shot while sitting in a car, as 11-month-old Yazeem Jenkins was, less than 24 hours before that.

Shot while getting off a bus in North Philadelphia, as a 16-year-old girl was Saturday afternoon.

A man walking up the street started shooting — “firing randomly as people were exiting the bus,” the acting police commissioner said — and he hit her in the left shoulder. The man was arrested at the scene and charged Sunday with murder, three counts of attempted murder, illegal possession of a gun, reckless endangerment, and related charges.

The teenager, identified as Ceani Smalls, of the 2200 block of West Cumberland Street, was pronounced dead at Temple University Hospital shortly before 5 p.m. Saturday.

The girl, a student at the Mathematics, Civics and Sciences Charter School in Spring Garden, was the 106th person under the age of 18 to be shot this year in Philadelphia.

It had been three days since a 16-year-old boy in Kensington and a 9-year-old boy in Southwest Philadelphia were shot in the chest in separate cases Wednesday morning.

“My heart aches so bad,” said Terrez McCleary, an activist whose 21-year-old daughter was killed in 2009. “It’s just over and over and over again that we’re losing our children.”

The support and advocacy group she runs, Moms Bonded by Grief, grows larger and larger.

As the gun-violence crisis continues to plague Philadelphia, the total number of victims is rising, and young people are making up a greater share. In 2015, children under the age of 18 made up about one out of every 16 shooting victims. Last year, they were one out of every 12.

Nearly 500 people under the age of 18 have been shot since the start of 2015, and the number is rising. The epidemic is not contained to Philadelphia: Saturday’s shooting came the same day that more than 1,000 people filled a church in Atlantic City to remember Micah S. Tennant-Dunmore, the 10-year-old boy who died after being shot at a Pleasantville-Camden high school football game in Pleasantville on Nov. 15. The gunfire stemmed from a fight among several men. Micah was an innocent bystander.

In Philadelphia, officials identified the accused gunman in Saturday’s homicide as Robert Ross Jamieson, 41, of North Philadelphia. Christine Coulter, the acting police commissioner, told reporters that he had been taken into custody by police at the scene Saturday, after Jamieson began randomly shooting around 4:40 p.m. near the intersection of 22nd Street and Sedgley Avenue, a few blocks from his home. Multiple witnesses had identified him as the gunman.

Court documents show a string of previous charges and convictions relating to possession and intent to manufacture or distribute drugs; burglary and theft; soliciting prostitution; and driving under the influence of drugs or alcohol.

Police found a 9-millimeter handgun at the scene, said CBS3, which first identified Jamieson as the gunman Sunday morning. It was illegal for Jamieson to have a gun because of a prior felony drug conviction, the district attorney’s office said in a statement.

For gun-violence activists and community organizers, the shooting had a familiar feel, prompting a sense of pain and frustration, anger and anguish. And, they said, a familiar set of questions: Where did the gun come from? Why was he allowed to shoot?

When does it end?

“Are people really going to wake up? I mean, what does it take for people to wake up and see that these things are really happening?” said Felicia Pendleton, a mother from North Philadelphia whose son was killed in 2016 while home from college for spring break. “Do you wake up when it happens to you? Do you wake up when it happens to someone in your family?”

Like others, Pendleton said gun violence is systemic, not individual, and tied to many other issues, including poverty, education, jobs, and mass incarceration. That makes it difficult for individuals to address. There’s no amount of doing the right thing, going to the right place, hanging out with the right crowd that protects children who are just getting off a bus or walking home.

“You can do everything that you’re supposed to do, and it still doesn’t make you exempt,” said Pendleton, who worries for her 17-year-old son — a young man who is working a job and preparing for college. “He’s doing everything right. But he can be getting off the bus and something happens to him, he can be coming home from work, he can be cashing a check. You’re scared these days.”

“It’s upsetting that teenagers can’t be teenagers anymore. Things that were once just part of coming up and growing up, like going downtown to go shopping, you have to be afraid. It angers me,” said Victoria Wylie, a South Philadelphia organizer whose brother was killed 11 years ago. “Here you have a teenager who’s doing what’s normal at her age, 16 years old, and getting off the bus, and I would say doing nothing wrong, and she’s a victim of gun violence.”

As a public-health crisis — more than 1,350 people have been shot in Philadelphia this year — gun violence looks different in Philadelphia than other parts of the state, said Anton Moore, a South Philadelphia activist who has long sought to address gun violence and poverty. Moore hopes to convince lawmakers from other areas to allow Philadelphia to enact laws that address gun-trafficking issues that affect the city.

“It’s not like we’re trying to change it in those counties they represent, we’re trying to change it in Philadelphia," said Moore, who envisions protesting in more rural areas to convince voters there to pressure their lawmakers. Philadelphia’s problems are different from rural areas, he said, and the gun laws should address different needs.

“It’s time for us to get brave," he said. “Too many kids are dying for us to just sit back and watch.”