The police have released an image of a teenage boy who fired a cap-gun in the direction of a transport worker at Wynyard railway station and filmed it on his mobile phone.

The male, who is believed to be in his late teens, approached a 58-year-old male transport worker at whom he fired the cap-gun about 2pm on Wednesday, police said.

Police have released an image of a man who fired a cap-gun at a train worker. Credit:NSW Police

As he fired the cap-gun in one hand, he used his other hand to film the startled reaction of the transport worker.

No one was injured in the incident.

Officers from the Police Transport Command are investigating the matter and have released an image of a male who may be able to assist with inquiries.

The male is described as being of Caucasian appearance, aged in his late teens, with a short buzz-style haircut.

At the time of the incident, he was wearing a dark grey T-shirt, black shorts, and black sneakers with white soles.