The other is believed to be the person who stabbed Ms. Majors and as of Friday evening was still being sought, according to a law enforcement official.

Columbia’s relationship with its surroundings has had many uneasy patches. The university, which has a huge endowment and owns scores of buildings, has been criticized by some longtime residents as a gentrifying force.

Tyrone Carter, 60, who works in a wine shop in Harlem, said that growing up in Harlem, he and his friends rarely ventured to Morningside Heights because it was “a different demographic.”

“People here lived through a heroin epidemic, a crack epidemic,” Mr. Carter said. “So being black in Harlem, some see it as invasion when young white up-and-comers start buying up buildings. I was born and raised in Harlem, and I can barely afford to live here now.”

Kevin Gates, 42, a teacher and lifelong Harlemite, said he was shocked by the killing, but not surprised.

“This area may have changed cosmetically, but it’s still New York City,” he said. “Gentrification has brought an influx of restaurants and night life, so a lot of the new people moving in here see it as some playground or utopia. But some get a false sense of security and forget it is still New York City.”

Morningside Park is in a Harlem police precinct that has grown safer over the years, but crime has risen this year in the park itself.