In the 1970s when Jeffrey Carter was attending Abraham Lincoln High School in Northeast Philadelphia, he and a group of friends were inseparable, often hanging out around Roosevelt Playground. He even married a member of that tight-knit group of friends — she grew up in the neighborhood, too.

Carter, a 66-year-old retired grandfather, drove by Lincoln High School on Monday afternoon, not far from his current home in the Fox Chase section of Northeast Philadelphia. A fight had broken out among a handful of students, and a 21-year-old gunman fired shots toward several teenagers who were running away, police said.

A stray bullet flew into Carter’s SUV and hit him in the head. He died less than two hours later.

“It’s like a nightmare to me,” said Robert Offenback, 65, a longtime friend and fellow classmate at Lincoln High. He said he and Carter kept in contact over the years, often catching up about fishing or cars or the upkeep on their houses. Mostly, though, Offenback said, they talked about their families: “He lived for his family.”

Philadelphia police on Tuesday identified Carter as the passerby who was killed when shots rang out Monday afternoon outside the school. A 16-year-old boy who is a current student was also struck in the head and remains hospitalized in critical condition, police said.

Carter was the 439th person to be killed in Philadelphia this year, which represents a 14% increase in homicides compared with this time last year. Most of the killings were committed with guns.

Charges have not yet been filed against the 21-year-old suspect. He was apprehended immediately after the shooting by plainclothes officers who were stationed near the intersection at Ryan and Rowland Avenues in Mayfair and saw the shooting, then ran toward the gunman, Police Commissioner Danielle Outlaw said.

She said authorities also detained a second suspect who may have been involved in the shooting, but it was unclear whether that person fired shots. The 21-year-old, she said, has a brother who had been a student at Lincoln, and detectives believe there was an ongoing dispute between him and the teenagers who were fired at.

A School District spokesperson said grief counselors were on hand at Lincoln on Tuesday to support students and staff experiencing trauma as a result of the gunfire.

Carter’s relatives, reached by phone Tuesday, declined to comment on the shooting.

Offenback described Carter and his wife as having “really a strong relationship.”

“They did everything together. That’s how they were,” he said. “They were just great people. They just don’t deserve this.”

He said he learned of the shooting early Tuesday morning and spent the day reliving memories built over nearly five decades of friendship. There were the many Labor Days spent at the Cannstatter German-American club in Northeast Philadelphia, and the summertime trips down the Shore. There were phone calls about topics as mundane as a broken washing machine — things Carter always knew how to fix.

Offenback, who’s known as Obie, said the last time he spoke to his friend was last Wednesday, when the two chatted about some work Carter was doing on a family home in Virginia. He’d just installed a new deck and had told a young relative: “One of these days, it’s all going to be yours.”

“Not even a week later,” Offenback said, “here he is gone.”