A teenage boy stopped by police officers for smoking a cannabis joint was found to be carrying a knife.
The 16-year-old was stopped in Burngreave on Friday afternoon by members of a new police team based in the city suburb in a crackdown on crime.
Police chiefs set up the new team following a spate of incidents including attacks in which one man was shot and another in which a teenage boy was stabbed in clashes between rival Kurdish and Somalian gangs.
The team is working from Sorby House on Spital Hill.
A spokesman for the Sheffield North East local policing team, said: "Following the recent trouble on Spital Hill, the new community team is now working from Sorby House, enabling them to link in with a number of partners and maintain a visible presence in the community.
"Judging by the community feedback so far, their presence is already having a positive effect and bringing results.
"On Friday afternoon, after seeing a 16-year-old local youth smoking a cannabis joint they detained him to deal with the drug matter only to find that he had a knife hidden underneath his clothing.
"He was subsequently arrested and dealt with for both offences.
"If you see the team on patrol around Burngreave please stop and talk to them."
To pass on information about crime in Burngreave call South Yorkshire Police on 101.