A 24-year-old man is accused of fatally stabbing a stranger who was a walking a dog when she was attacked in Washington, D.C.

Eliyas Aregahegne was arrested Wednesday and has been charged with first-degree murder in the fatal attack Tuesday on Margery Magill, 27.

Police said officers were called to a report of an unconscious person on Irving Street NW around 8:50 p.m. and found Magill with multiple stab wounds. Nearby residents were providing medical aid before she was taken to a hospital and died, officials said.

Magill was working as a dog walker when she was stabbed, D.C. police Chief Peter Newsham said.

"Margery was a young professional who just received her master's degree in international relations, and who by all accounts was beloved by her family and friends," Newsham said at a Wednesday news conference.

A motive has not been determined, and the police chief said that detectives have found no evidence to suggest the attack was an attempted robbery or sexual assault. He called the type of attack very rare.

Aregahegne appears to be a stranger to Magill, Newsham said. He said investigators don't have any information that drugs or alcohol were involved.

Detectives tracked Aregahegne to a nearby residence where he was arrested Tuesday night. He was charged Wednesday morning, Newsham said. The police chief said that the number of video cameras in the area played a key role in the arrest.

Chris Chambers, who lives near the scene of the fatal stabbing, told NBC Washington that he heard “a scream and then an 'Oh no!' and then another scream," and that he and his wife went out and found a dog loose with a leash.

When they saw the animal, "we knew something was wrong," and they looked down and saw the young woman bleeding, Chambers said.

Raeann Magill called her sister's death "absolutely tragic" and told the station that it’s hard to understand how her sister could be stabbed while walking a dog. "How can anyone even fathom that? I mean, it's truly tragic and I even think to myself, 'why her?'"

Her family told the station that she grew up on a small ranch in California.

"She loved the city. She loved the energy. She really wanted to build her career here and thrive off of the energy that was Washington, D.C.," Raeann Magill said.

Newsham said that Aregahegne has a criminal history but he did not go into details Wednesday. He was being held in custody late Wednesday, a jail official said. It was not immediately clear if he had an attorney.