Police have arrested a 24-year-old D.C. man in the fatal stabbing of a woman who was walking a dog on Irving Street NW in Park View.

Margery Magill was walking a dog for a family who lived in the area just before 9 p.m. on Tuesday night when a man came up and stabbed her, Police Chief Peter Newsham said in a press conference about the incident on Wednesday. Neighbors in the area heard her screaming and begging for help, but by the time they came outside and found her, the suspect had fled on foot, according to Newsham.

“It was a terrible scream,” said Chris Chambers, a professor at Georgetown University who lives nearby. Chambers, his wife, a neighbor, and a passing couple found Magill lying on the sidewalk and tried to render aid, staying with her until ambulances arrived.

Chambers told DCist that he and his wife Dianne, who works as a business research analyst in the District, were relaxing at home when suddenly they heard what must have been the attack: first a loud scream, and then shouts of “oh no!” and “help me!” Magill screamed one more time and then fell silent, he says. The whole thing lasted no more than ten seconds.

When Chambers walked onto his porch, he saw a dog across the street with a leash but no human, he says. Then he saw Magill lying on the ground nearby, already unconscious and gravely injured. He tried to perform chest compressions, and then called a neighbor over for help. By that time, he thinks Magill was probably already gone.

“It was horrible. We kept trying to help her because that’s all you can do,” he says. “Even though we knew in our hearts she was probably gone.”

On Wednesday, police arrested Eliyas Aregahegne of Northwest D.C. in the stabbing, and charged him with first degree murder while armed. Detectives found Aregahegne using surveillance cameras in the area and other forensic evidence, Newsham said. He was eventually located in a home on Columbia Road NW, where detectives recovered more evidence, he said.

Aregahegne has a criminal record, per Newsham, though he did not specify what that record contains. A person with Aregahegne’s same name and age was reported missing by MPD in 2017. The release at the time said that he “may be in need of medication.”

The attack happened on a populous street, near the Washington Hospital Center and a popular community garden. “There were people everywhere, walking dogs. This was 8:30 on a Tuesday night,” says Chambers.

The suspect and Magill did not appear to know each other, according to police. The attack did not appear to be a robbery or an attempted sexual assault, and police have been unable to discern any apparent motive so far, Newsham said. Police also do not have reason to believe that drugs or alcohol were involved. While investigators are still assessing a possible motive, Newsham said that he “wouldn’t say it was out of the scope of possibility that it was random.”

If that turns out to be the case, Magill’s would be the third random murder of this nature in the last year alone. Last September, a woman named Wendy Martinez was brutally stabbed while out for a run in Logan Circle. She and her attacker did not know each other and the attack appeared to be random and unprovoked. Last week, a 62-year-old bridge inspector was stabbed with a pocket knife while on the job by a person who later told police the devil told him to do it.

Newsham stressed at the press conference that these incidents remain rare in the city. “This is a very very safe city. This type of incident is very rare,” he said. “The District of Columbia is not unlike any major city in the country, whenever you go out, regardless of your gender, you should be cautious and alert.”

Homicides in D.C. are up by 13 percent this year.

Magill was 27 years old and had recently moved back to D.C. to work as a program coordinator for a fellowship at The Washington Center, according to her LinkedIn page. She graduated with a bachelor of science degree in international agricultural development from the University of California, Davis, and with a master’s degree in international relations from the University of Westminster.

She walked dogs in the District for Rover, a kind of Uber for dogwalking, according to the Washington Post. (Chambers says although he didn’t know Magill, he recognized her from walking dogs in their neighborhood all summer. “She was always walking a dog,” he says.)

“[Margery] had more of a life in her 27 years than a lot of people have in their whole lives,” her father Jeffrey Magill told the Post. She loved to travel, and lived in or visited an array of different countries: Costa Rica, Tanzania, Nicaragua, Turkey, and Zanzibar, he told the outlet. She had been living abroad for the last two years in Istanbul and Turkey and moved back to D.C. for her “latest adventure,” she wrote on her LinkedIn.

“It’s absolutely tragic. I still can’t wrap my head around it,” Magill’s sister, Raeann Magill, told NBC Washington. “You know, out walking a dog and to be attacked like that. How can anyone even fathom that? I mean, it’s truly tragic and I even think to myself, why her?”

Dianne Chambers says she hasn’t been able to think about the incident or Magill without crying. She says neither she nor her husband are fearful people, and they plan to continue on normally with their lives. But she is deeply sorry they couldn’t do more to help Magill that night.

“Where this woman was, there were so many people around her who were caring people and who really wanted to help,” she says. “And we want her family to know that we did what we could, and we tried, and we’re very sorry she’s gone.”