D.C. police charged Kyla Jones with the stabbing death of Kaelia Minor, 17. Police say Minor and Jones got into an argument on Oct.18 while aboard a Metrobus headed to Petworth that escalated into a physical fight. (WUSA)

Kaelia Minor had finished dance rehearsal at Coolidge High School and was riding the No. 62 bus home from Takoma to Petworth. It was about 8 p.m. Monday, and the bus ride was anything but peaceful.

Authorities said Minor, 17, and another young woman got into an argument about a cellphone, the latest flare-up in a long-running dispute. The shouting continued when the bus reached Minor’s stop at Emerson Street and Kansas Avenue, three blocks from the Coolidge senior’s home in Northwest Washington.

In seconds, D.C. police said, Minor was stabbed in the chest, and detectives were searching for a young woman with a knife. Minor died at 8:29 p.m. at MedStar Washington Hospital Center, the District’s 110th homicide victim of 2016.

An arrest was announced by D.C. Mayor Muriel E. Bowser (D) at a news conference Tuesday. Police identified the suspect as Kyla Jones, 18, of Northwest. They said that she was charged in a warrant with second-degree murder while armed and had turned herself in.

Details of the dispute that authorities said preceded the stabbing were unclear Tuesday night. But whatever it was about, it was “not important enough for a 17-year-old to be dead” and for a second person to have “signed her life away,” the mayor said.

In addressing the overall issue of violence in the District, Bowser said, “We are trying like crazy to find solutions.”

“We don’t value other people’s lives no more,” said Minor’s cousin, Bobleto Latta, 44, who lives in Anacostia and heard about the stabbing while working the night shift as a plumber at the Rayburn House Office Building on Capitol Hill. He raced to the stabbing scene at 2 a.m., not knowing whether Minor was alive or dead, or even if the report was true. “I just don’t understand this.”

D.C. police said the fight started with an argument aboard the Metrobus between Minor and another teenager or young woman. Police said the two knew each other and had been feuding for a long time. Latta said Minor had told relatives about trouble with another teen but had not gone into detail. Police said they were reviewing surveillance video from the bus as part of the investigation.

The news sank in Tuesday. A school system official confirmed that Minor attended Coolidge, in Takoma, about 11/2 miles from her home off New Hampshire Avenue near Fort Totten. References to the school and to dance, her passion, fill her Facebook page, and she posted on Twitter her plans for an exciting future: “college in a few months and im just like damn im really . . . outta dc im so excited.”

Latta said Minor had been accepted to Drexel University in Philadelphia and to other colleges that he could not recall. “She hadn’t picked one yet,” the cousin said. “Dance was the top thing that she really loved.”

He said she captained the school’s dance team, and a Twitter account set up in her memory showed classmates hanging a banner honoring her achievements. One student tweeted: “Coolidge aint the same today.”

Other relatives, including her mother, did not respond to interview requests. She has two brothers in their early 20s, and she lived most of her life in Northwest. Richard Jackson, the principal at Coolidge, declined to speak to a reporter about Minor.

Though just 17, Minor had filled out an online résumé that listed completed community service hours and leadership positions in dance groups. It also said she was on the honor roll.

Latta said that when word spread about the stabbing Monday night and early Tuesday, he hoped the news was wrong. “I was driving up there, and all this stuff was swirling in my head,” the cousin said. “I didn’t know if it was true, and was hoping it was not.”

When he went to the scene and saw the crime scene tape , “I knew, unfortunately, it was true.”

Jennifer Jenkins, Perry Stein and Martin Weil contributed to this report.