A knife-wielding man has been shot dead in Sydney's southwest after he allegedly attempted to stab a police officer.
Emergency services were called to Bird Walton Avenue in Middleton Grange, about 40km from the CBD, about 11pm on Saturday following reports a man was armed with a knife.
Police said the 34-year-old allegedly confronted and threatened officers on arrival, with 33-year-old male officer struck with the knife but protected by his operational vest.
A Taser was used but proved ineffective before police shot the man.
The police officer was not injured.
A critical incident team from the state crime command's homicide squad will investigate the circumstances of the shooting and the probe is subject to an independent review.