Detectives from Transit Crime Investigation unit are investigating an armed robbery which occurred in Berwick about 6pm on 14 June.
Investigators have been told the victim, a 16-year-old boy, was at a skate park off Clyde Road with three friends.
They were approached by three males who attempted to speak to the group before producing a knife and stealing a satchel and earphones from the victim.
The investigation is ongoing.
Detectives are also investigating an attempted robbery which occurred near the Berwick Railway Station about 5.30pm on 14 June.
The victim was approached by four males who threatened him and attempted to steal his jacket.
He managed to make it to a bus before the offenders walked off.
Fortunately there were no injuries.