The incident occurred early Sunday morning on a Hoboken-bound train. Port Authority police spokesman Joe Pentangelo says police received a call at about 1:20 a.m.
Passengers told police the group assaulted and robbed them. One of the victims, a 21-year-old from Budd Lake, received eight stitches in his lip. Other victims suffered lacerations and bruises.
After the passengers provided descriptions, police arrested the suspects in Hoboken Terminal. One of the victims' wallets was recovered.
Pentangelo says the six are between 15 and 17 and hail from Newark. They are charged with gang assault and robbery and are being held in the Hudson County juvenile detention facility.