Police officers are visiting Sheffield schools today for information on the murder of a city teenager.
The visits, before schools break up for half term today, have been organised following the fatal stabbing of a 15-year-old boy in Lowedges last night.
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He was found seriously injured in Lowedges Road at 7.50pm and was pronounced dead in hospital an hour later.
His killer has not yet been arrested.
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Today, Sheffield's District Commander, Chief Superintendent Stuart Barton, said: "We're going to schools in the area today to reassure them about what we're doing and to ask anyone who knows anything to come forward.
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"If anybody is sitting on that information they need to open their mouths. That will hopefully give the boy's family the reassurance that we can do what's needed to bring whoever's responsible to justice."
He added: "We've already visited many schools around South Yorkshire, especially in Sheffield, and spoken to over 20,000 young people around the dangers of gangs and gun and knife crime.
"We need to filter that message through to parents and loved ones of these young people so they can take some responsibility.
"Knife crime is a partnership issue and a societal one so we all have to take responsibility."
Chf Supt Barton said detectives are working to establish the motive for the attack.
He added: "We're still trying to piece together what's gone on, and we're not sure at the moment of any motive."
"I believe there are people out there who know what's happened and who's done this. They need to either speak to officers at the scene or ring us to provide us with those pieces of the jigsaw we need.
"This boy is two or three years younger than my son, and I can't imagine what his family are going through.
"We believe there may have been a degree of targeting. We don't believe at this time it was a random attack."