The man who allegedly unleashed at least 50 bullets on random members of the public in Sydney on Sunday night had no known mental health history, according to police.

Axar.az informs, citing ABC, tactical officers exchanged gunfire with the 60-year-old man in Croydon Park, located in Sydney's inner west, in what they described as a "highly dangerous operation".

Croydon Park was plunged into lockdown just after 7:45pm on Sunday following reports of an active shooter.

Locals ducked for cover as the alleged gunman fired shots from the window of a unit above a business on Georges River Road, with bullets striking vehicles and a nearby bus shelter.

Acting Superintendent Stephen Parry said between 50 to 100 shots were fired "indiscriminately" at passers-by over a two-hour period.

One man, aged in his 50s, was shot in the neck and chest. He was taken to hospital in a critical condition and underwent emergency surgery.

The alleged gunman was arrested at about 9:30pm, with police still seeking to uncover a motive.

Croydon Park is a multicultural suburb with mixed-residential housing that is popular with young families.

The road where the shooting occurred has a series of eateries and fast food places, and is nearby a school and church.