Police are investigating after an alleged armed robbery in Sydney’s south.

About 10.30pm on Sunday 17 July 2016, emergency services were called to a licensed premises on George Street, Mortdale, following reports of an attempted armed robbery.

Police have been told, two males, who allegedly produced a firearm, entered the premises, before threatening employees and demanding cash.

One man fled the scene as the other man was detained by a number of people who witnessed the incident.

NSW Ambulance Paramedics treated the man at the scene before taking him to St George Hospital for minor injuries,

The man remains under police guard at hospital.

No one else was injured.

Officers attached to St George Local Area Command canvassed the area and commenced an investigation.

A short time later police located a vehicle, believed to be connected to the incident, at Acacia Avenue, Oatley.

Police arrested two men and a woman before being taken to Kogarah Police Station and Sutherland Police Station, where they are currently assisting police with inquiries.

Charges are expected to be laid.