One "young person" is under arrest and police are searching for at least one other after a 17-year-old boy was allegedly stabbed to death near a school in Sydney's north-west.
Police said the boy was one of two people approached by two or three other boys at a reserve in Beaumont Hills just after 4.20pm today, outside Ironbark Ridge Public School.
They believe a conversation led to one of the boys pulling out a knife, allegedly stabbing the 17-year-old in the thigh.
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They're alleged to have fled before a number of female witnesses at the park called emergency services and attempted to render first aid.
Despite the best efforts of paramedics, the boy died at the scene due to his injuries.
Police said a "young person" presented themselves to a police station with their parents about 7pm.
They were placed under arrest and were assisting police with investigations.
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One or two other males believed to be in the group have not been found.
Speaking to media tonight, Superintendent Naomi Moore called the event a "senseless" tragedy.
"It's a tragic situation. I have 17-year-olds at home, this has impacted the core of the community," she said.
"It is, I have no other words but it's just tragedy and it's senseless."
Moore stressed ongoing investigations were in their infancy. She said she didn't believe what happened was a random attack but there were no signs to show it was gang-related.
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"I don't believe it was random, I believe there is potentially some connection [between the groups]," she said.
Moore praised the work of the bystanders who tried to save the boy's life, saying they showed great courage despite potential risk to themselves.
"It would have been a horrifically confronting situation for those people, and I can only praise them for their efforts," she said.
"It was a potentially dangerous situation they were walking into, but they thought nothing of themselves to go in and render aid."
Member for Greenway Michelle Rowland said she was "deeply saddened" by the killing, and expressed her condolences for the boy's family.
"Deeply saddened to learn of the tragic loss of a young life in Rouse Hill this afternoon," she said in a statement on social media.
"My thoughts and deepest condolences are with the young boy's family during this extremely difficult time.
"There is no place in our community for these acts of senseless violence, and I know this news will be particularly distressing for local families."
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