A Star reader, who asked not to be named, said officers carrying guns were on Leighton Drive in Gleadless Valley at around 10am today.
He said two armed officers had initially got out of their car and started walking towards the block where he lived.
"It was a little bit unnerving," he said.
He said they eventually went into another block of flats, while another police vehicle with a further two officers inside waited on the street.
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He said the officers came out of the building and it appeared nobody had been arrested.
South Yorkshire Police have been contacted for comment.
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