Operation Mach, which will run for another week, aims to snare around 100 individuals, many of whom are "self-professed role models" who entice vulnerable youngsters into a life of crime. The huge police operation would never have taken place, however, were it not for the work of South Yorkshire Police Superintendent Peter Norman, who said "enough is enough" after teenagers Tarek Chaiboub and Jonathan Matondo were shot dead in the Burngreave area of the city in 2007 and 2008. Their deaths signified the spiralling gang problems in Sheffield, with the city's two most prominent "postcode gangs" – the S3 and S4 crews – not afraid to kill over the most petty of differences. Supt Norman said: "We were aware of a small gang problem but we used to say that things were isolated incidents. After the shooting of Tarek Chaiboub, I put my head above the parapet and said we weren't taking things as seriously as we could and should. "I got a lot of support so we sat up, took notice and put a lot more resources into it. That's why Operation Mach has gone ahead. "Hopefully this will be the spark that sets things in motion." Tarek was just 17 years old when he was shot at Frenchie's barber shop in the middle of a summer's afternoon on July 11, 2008. His murder was ordered by S3 gang leader Nigel Ramsey from his cell at HMP Wolds, following the near-fatal stabbing of Ramsey's cousin, fellow S3 member Junior "Bam Bam" Liversidge. The S3 gang had previously split into two factions, a feud which was responsible for the fatal nightclub stabbing of 23-year-old Brett Blake in June 2008. Two friends of Blake's killers then stabbed Liversidge the day after Blake's funeral. Tarek, who had a foot in both camps, was branded a traitor by the Liversidge camp and was stabbed within 24 hours by Michael Chattoo, 21, and Javan Galloway, 20. Despite suffering a perforated liver, he survived the stabbing, only to be shot in the back five days later by one of three hooded men – Chattoo, Nigel Ramsey's brother Denzil Ramsey, 20, and 17-year-old Levan Menzies. All five denied the charges but were all found guilty by a jury. The four convicted of murder were jailed for life, while Galloway was sentenced to nine years. Sixteen-year-old Jonathan Matondo – also an S3 gang member – was shot dead at Nottingham Cliff recreation ground in October 2007, less than a year before Tarek was killed. Nobody has ever been found guilty of his murder. Jonathan, known as "Venomous", had arrived in Sheffield in 1999 after fleeing the Democratic Republic of Congo with his mother Theresa Mfuilu. He was a keen churchgoer who had considered entering the priesthood but, by the time of his death, he had become embroiled in gang culture. When he died, Jonathan was on a supervision order for a robbery and had been in trouble with the police several times previously. Although his killer has never been found, police believe it was a member of the rival S4 gang.. Supt Norman said: "The case of Jonathan Matondo is not closed. If we do get any new information it will immediately be looked at, and we're always making advances in forensic technology. The tragic deaths of these two young boys were a wake-up call. "Since then we've done a lot. New data I received yesterday shows that serious youth violence in South Yorkshire has reduced by a fifth over the last six months. "Diversionary activities seem to be working, and I'm confident these latest arrests will also make a huge difference." Help on offer to drug addicts AS WELL as removing gang leaders and diverting youngsters from a life of crime, Operation Mach also aims to help those addicts dependent on the city's drug dealers. Agencies such as Sheffield's Drug and Alcohol Action Team (have been working with the police to show addicts where they can get help. A former heroin user who has become a drug treatment worker commended the police's hard-hitting operation. The 32-year-old grandmother, who has now been clean for 10 years, said: "I started using drugs when I was 15. I wasn't living a life, I was existing. "It's fantastic what the police are doing because it forces people to make that choice and shows them the amazing, free treatment that's available to them."