A witness reported that an adult male was fighting with three juveniles in the bus zone. One of the juveniles stabbed the adult with a pocket knife. The suspects were described as a black male and two black females, all about 17 years old. The suspects fled toward Millbrae Avenue and were not located. BART and San Mateo County Sheriff's units responded. The victim was uncooperative and refused to provide a statement. The victim suffered a minor, non-life threatening cut to his back. The victim was transported to SF General Hospital. TSOC notified.