A 21-year-old man has been shot by police during an incident at a residential property in Glen Alpine, in Sydney's south-west, prompting an independent investigation into the use of police firearms.

NSW Police said officers were called to a home at approximately 12:25pm on Thursday, 22 October, after receiving reports of threats involving a man and a woman. According to police, threats were allegedly made against the woman during a Triple Zero emergency call before officers arrived at the address.

Assistant Commissioner Stacey Maloney said officers encountered a man allegedly armed with a pistol. Police allege that the man pointed the firearm towards officers, who then shot him in the stomach.

Officers immediately provided first aid before paramedics continued treating the injured man. He was subsequently transported to hospital in a serious condition.

The woman involved in the incident was also taken to hospital for treatment after experiencing shock. Police have not reported any other injuries connected with the confrontation.

Authorities said there had been no previous reports of domestic violence incidents involving the address and no recorded Apprehended Violence Orders relating to the matter. Investigators have not publicly released further details about the relationship between the man and the woman or the events leading up to the emergency call.

A local resident told ABC News that he heard several shots fired in quick succession. When he looked outside, he saw police officers attending to someone lying on the ground. Additional police vehicles and ambulances arrived shortly afterwards.

Following the shooting, police established a crime scene around the property and declared a critical incident. This procedure allows the circumstances surrounding a serious police incident to be independently examined.

The Professional Standards Command will conduct a review overseen by the Law Enforcement Conduct Commission, the independent body responsible for overseeing police conduct in New South Wales. The review will examine the circumstances of the shooting and the actions taken by officers.

Police have not announced criminal charges against the injured man in connection with the incident. The allegations about the threats and the firearm remain subject to investigation, and the full sequence of events has not yet been established publicly.

The incident has renewed attention on the risks faced by emergency responders when attending reports involving alleged domestic violence and firearms. Investigators will need to establish the evidence surrounding the confrontation, including the circumstances in which the weapon was allegedly presented and the decision to discharge police firearms.

The investigation remains ongoing, and further information may be released after the independent review progresses.