Man shot dead by police called to shopping centre brawl

A man in his 20s has been shot dead by police at a suburban shopping centre after he allegedly threatened them with a machete.

Uniformed officers fired several shots at the man after he threatened them during a brawl at a shopping centre car park in Sydney's west on Saturday, NSW Police said.

The man died at the scene about 4pm after police and paramedics tried to treat his injuries.

A crime scene has been established at the Mount Druitt Westfield and a critical incident has been declared.

State Crime Command's homicide squad will lead a probe into the incident with oversight from the Professional Standards Command.

Police were called to the shopping centre car park on North Parade at about 3.15pm following reports a fight had broken out between two groups.

A Scentre Group spokesperson said its team was assisting authorities.

"The safety and security of our customers, business partners and people is our highest priority," the spokesperson said.