Two girls were threatened with what is believed to be a knife by a man as they were by the James Paget University Hospital.
The girls, who were aged under 13, were on Lowestoft Road in Gorleston when they were approached by the man.
He threatened the victims with what is believed to be a knife, before the girls ran away and called the police.
The incident happened at about 9.30am on Monday, November 20.
The suspect was white, aged in his early 20s, of a muscular build and was wearing a black jacket, Nike Air Max trainers and had a black bandana across his face.
A police spokesman said: 'Officers would like to hear from anyone who may have witnessed the incident or has information concerning it.'
Witnesses should contact PC Adrian Young at Gorleston Police station on 101.
Alternatively people can also call Crimestoppers anonymously if required on 0800 555 111.
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