Detectives revealed the quartet were attacked by six men in an alleyway off Kendal Close, near Booth Lane North, between 8pm and 8.10pm on Saturday, January 18.
A Northamptonshire Police spokesman said: "Four friends were approached by a group of six males, who had their faces covered and had various weapons.
"The offenders threatened the four men and demanded they hand over their property before assaulting them with the weapons and running off in the direction of Repton Close.
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"The offenders are described as black males, about 5ft 11in, with black and white face coverings and wearing black clothing with the hoods up. The weapons included a knife, metal poles and wooden bats.
"Anyone with information or who may have seen this incident or have any information can call 101 quoting reference number 20000034094."