Pupils and teachers at Muizenberg High School in Cape Town are in mourning after matric pupil Janet Ntozini, 18, was murdered while trying to protect a vulnerable person in her community over the weekend."Our information is that she tried to intervene when a community member was allegedly beating up a disabled boy," Jessica Shelver, spokesperson for provincial education MEC Debbie Schafer, said on Wednesday.Western Cape police confirmed that she was stabbed three times after an altercation with a man in Vrygrond.Captain FC van Wyk said she had been rushed to hospital, but died there as a result of her injuries.Officers arrested the 23-year-old suspect on Sunday evening and he appeared in the Muizenberg Magistrate's Court on Tuesday.Residents went on the rampage after the stabbing, with Van Wyk confirming a house in Vrygrond had been vandalised and cars were burnt in Doring Street.The owner of the house, who is not a suspect in the murder, declined to open a criminal case.'Our hearts are broken'Ntozini had shown great promise as a student and soccer player, according to her principal and the Western Cape Education Department.Principal Leonie Jacobsen told News24 on Wednesday that the death was a tragedy and that they acknowledged Ntozini as a "hero"."Our hearts are broken... she was a success, a turnaround story in education. She was at risk, a girl who truly could have gone the other way and been a statistic."Her values were fantastic. Her acute sense of community eventually made her interfere in something that left her vulnerable and at risk."Shelver said Ntozini had achieved excellent academic results last year and that provincial soccer scouts had recently seen her play.'She was a tough cookie, but a real team player'Jacobsen said they had encouraged Ntozini to pursue her soccer career after school."She was an excellent soccer player. She had Banyana Banyana potential. She was a tough cookie, but a real team player."At the school, distraught friends and teachers lit candles and placed flowers beneath posters, with the words "RIP Janet" and "For the hero in all of us".Counselling was being provided for her friends and others at the school who needed it.Shelver said: "She died as she lived – courageous and brave, standing up for those who were not able to stand up for themselves. She had a very bright future ahead of her and the school community is devastated by the loss of such a young, beautiful life."The school will hold a memorial for her on Wednesday and has asked everyone to wear pink, Ntozini's favourite colour.Her family would then travel to the Eastern Cape to bury her.