Officers executed 10 warrants of teenage boys on Tuesday morning - including one from Portsmouth - following a spate of incidents in Southampton city centre throughout June, July, August and September.
Gangs of robbers preyed on teenage victims walking on their own - some of whom were threatened with a knife.
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Officers have now arrested 15 boys aged between 13-years-old and 16-years-old in total.
Three teenage boys were also arrested in connection with the crimes last month before being released on bail as enquiries continue.
Twelve boys remain in custody today.
Officers are increasing patrols in the area.
Det Sgt Russ Smith said: ‘We fully understand the impact these types of crimes have on victims, as well as parents and on communities. We want to reassure you that we are working hard to identify all those involved and keep people safe.
‘If you have any concerns or information please don’t hesitate to speak with patrolling officers.
‘Tackling violence and knife crime in our city remains an absolute priority for us but it depends on partnerships across a number of sectors, not just the police, it includes education, housing, social and youth services.
‘Every agency is crucial in supporting the city move towards a future free from violence and tackling the root causes of violent crime.
‘We urge communities to keep reporting intelligence around knife crime so that together we can continue to tackle this threat in society.’
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Call 101 with information quoting reference 44210357746 or go online at https://www.hampshire.police.uk/
People can also report incidents to Crimestoppers on 0800 555 111 or online at https://crimestoppers-uk.org/
Young people can report anonymously online at Fearless.org