An adult and two juveniles were arrested for an armed robbery by knife last evening. On Tuesday, 12-08-2015 at 18:59 hrs, Brookline Police responded to Griggs Park for a report of an Armed Robbery. The victim stated that 6 young males had beat him up and robbed him at knife point; stolen was money, a cellphone, and a coat. Officers located 3 individuals a short time later near the scene of the incident and during a show up identification, the victim positively identified 3 of the individuals . All 3 were placed under arrest and charged with Armed Robbery and Assault & Battery.