A man was robbed of his mobile phone, his glasses and an E-cigarette in Stamford Road, Kettering.
The incident happened just before 1am on Sunday, 7 February.
The victim was walking along Montagu Street when he noticed the men standing just inside Water Street. The men approached him and threatened him verbally before standing in his way.
He managed to cross into Carey Street and continued up Stamford Road. The offenders followed him and then knocked him to the floor before robbing him.
They are all described as black with a slim build and wore black jackets with the hoods up and scarfs across their faces. They were in their late teens to early 20s. One was about 6ft and the other two slightly shorter.
Witness or anyone with information about this incident can contact police on 101 or Crimestoppers anonymously on 0800 555 111. Alternatively you can use their anonymous online form at www.crimestoppers-uk.org