Bennett Brookstein didn’t expect a lot of people for his club’s regular run last Saturday: It was Christmas morning, after all, and he showed up at dawn, alone.

The Philadelphia schoolteacher also didn’t expect to get punched a little while into his route, or cut with a steak knife. Yet, he was.

On Thursday, police confirmed an arrest had been made in the attack that has generated widespread concern among the running community.

Rami Muhammad, 35, has been charged with aggravated assault, possession of an instrument of crime with intent, simple assault, and recklessly endangering another person, according to court documents. Bail is set at 10% of $50,000, and Muhammad is being held at Curran-Fromhold Correctional Facility pending a hearing scheduled for Jan. 12. No address was given for him; police said Muhammad is experiencing homelessness. He is to be represented by the Public Defender’s Office, records show.

In an interview Thursday, Brookstein said he was grateful for all the support runners — from his neighborhood and around the country — have shown him, flooding social media with notes and pictures dedicated to him, and joining a Wednesday night run in his honor.

Brookstein, who lives with his family near the Art Museum, told The Inquirer he was settling into his familiar 3-mile loop on Martin Luther King Jr. Drive, near the St. George and the Dragon statue, Christmas morning when a man “larger than me” called out to him.

As founder of the Fairmount Running Club in 2003, and a veteran health teacher in the Camden and (since 2016) Philadelphia public schools, Brookstein was following standard safety guidelines: “People say you should run in the daylight” -- he started at 7:30 a.m., around dawn. “I don’t wear headphones — you want to hear, and know your surroundings.”

He was, however, running alone, as he has done more often during the pandemic. (The club was founded in part so members could more easily run in groups.) But Brookstein was running on well-trafficked streets, on the same loop he’d traveled without incident many times, including Friday, the day before, when he started half an hour later.

The stranger asked if Brookstein had anything for him, according to Brookstein. “I was startled. I paused. My thing is always, I’m trying to help people: ‘What do you need?’ So I stopped.

“That’s when he started throwing punches at me. He kept pounding me in the head. And a couple body shots.”

Brookstein said he moved to defend himself. He turned south, toward the Art Museum. Seeing three runners, he yelled for help, and they headed toward him. He heard a metallic clatter on the pavement. One of the approaching runners called out: “It’s a knife,” adding that Brookstein had blood on his running shorts, and his back.

He had been stabbed in the buttocks, police said later. He and the runners converged, leaving the attacker behind. Brookstein took out his phone and called 911.

“The paramedics showed up first” and cut off his shorts to check his injuries. “The police came a minute later. They put me in the truck” and rushed him to Penn Presbyterian Medical Center, where staff treated his deeper wound with antibiotics.

Brookstein’s not sure he could have outrun the man who confronted him. “He looked fit. The police officer said I must be pretty strong, to take a bunch of hits from this guy.”

He says the attacker didn’t leave the scene entirely, instead hanging around until he was taken into custody by police, who then took him to the hospital for Brookstein to identify.

Wednesday is a regular running day for the Fairmount Running Club. This week, leaders of the Philadelphia Marathon, for which Brookstein served as an “ambassador” as well as a participant at this year’s race last month, urged runners to join the usually small winter group run in Brookstein’s honor. So did Jim Marino, former race director of the Broad Street Run.

Brookstein stayed home on doctor’s orders. “My head is still pounding,” he said. “He hit me in the face, and in the jaw.”