An armed robber has bashed two young women and a boy who were working at a fast food outlet in Sydney’s west.

The man hit a crouching 16-year-old girl on the head as he pushed his way into the Merrylands establishment early on Sunday night.

He then punched a 15-year-old boy in the head before grabbing the manager, a 24-year-old woman, by the neck and slamming her head into a wall.

Police say she was forced to open the safe.

The robber, who was armed with a silver handgun, then ran off with cash and a handbag.

The boy was taken to Westmead Hospital with a cut to his head. Police have established a crime scene and are searching for the man.

He’s described as being of Mediterranean or Middle Eastern appearance, with a slim, athletic build.

In a separate incident on Sunday night, a 26-year-old male cashier was robbed at knife point.

The robber walked behind the counter of the Balgownie service station, threatened the worker and took cash and cigarettes before fleeing.

Police and the dog squad searched for the man but were unable to find him.

He’s described as being of Caucasian appearance, about 180cm tall with a solid build.

AAP