A critical incident investigation is underway after a young man allegedly armed with a pistol was shot by police in Sydney’s southwest.

Emergency services were called to Strathmore Pl near Mountain View Ave in Glen Alpine about 12.25pm on Thursday following reports a man had made threats. 

Officers arrived to find a 21-year-old man allegedly armed with a pistol.

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A confrontation followed, during which the man was shot by police.

Officers immediately provided first aid before paramedics arrived and took over treatment.

The man was rushed to hospital in a serious condition.

No other injuries were reported. 

A 21-year-old man was rushed to hospital in a serious condition after being shot by police in southwest Sydney. Credit: 7NEWS

The 7NEWS helicopter captured officers and paramedics at the home after they’d secured a perimeter with police tape.

Personal items were seen strewn across the front lawn while officers led two men away from the property in an unmarked police car.

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A crime scene has been established, with a Critical Incident Team from Burwood Police Area Command investigating the circumstances surrounding the shooting.

The investigation will be reviewed by the Professional Standards Command, with oversighted from the Law Enforcement Conduct Commission (LECC).

The home is about 1.4km northwest of where 23-year-old Marco Tapia was allegedly shot dead in a case of mistaken identity on September 1.

More to come ...