In an interview, Kevin Sampson, a dean at school, said the fatal confrontation stemmed from “bullying,” and at a news conference on Wednesday afternoon Chief Boyce said it appeared the three students had been locked in a running dispute over the first weeks of the school year, and that it blew up inside a fifth-floor history classroom around 10:45 a.m. in front of about 20 other students.
The stabbings — and the presence of a switchblade in the school — stirred complaints from some parents that the school did not have metal detectors and prompted questions from reporters to the mayor and police officials about whether the school should have had them. Eighty-eight of the city’s roughly 1,300 school buildings have metal detectors that are used either full time or part time.
Among students and faculty, though, the talk was of the lives changed.
Shortly after they were released from the lockdown on Wednesday afternoon, Asia Johnson and Yanique Heatley, both 18, stood outside the high school at 2040 Mohegan Avenue in the West Farms neighborhood.
The two were friends with all three of the students involved, they said. Ms. Heatley described Mr. Cedeno as “different from the other guys.”
“He likes Nicki Minaj, stuff from H&M. He likes Kylie Jenner,” she said.
“This hurts,” Ms. Johnson said. “No one should experience bullying but there’s a way to handle it.”
“It’s really sad,” Ms. Heatley added. “Two boys might lose their lives and our friend will never see the outside again.”
Mr. Sampson, the school’s dean, stood, visibly shaken, outside on Mohegan Avenue. He had performed CPR on Matthew, he said. “Two of my students got stabbed and one of them died,” Mr. Sampson said. “It was about what it’s always about — bullying.”
At a news conference with police and school officials, Mayor Bill de Blasio said the death had shaken him and many others in the community and the city government.