07/03/2016 11:37 AM AEDT | Updated 15/07/2016 12:51 PM AEST

Gunman Dead After Stand Off With Police, Three Shot In Sydney

The gunman who killed one man and held hostages inside a Sydney industrial site on Monday is dead after a six-hour stand-off with authorities.

Police have confirmed the gunman died from a self inflicted wound and investigations of the crime scene at Inline signage factory are under way.

Three hostages were led out of the building moments before by police and taken to hospital on Monday afternoon.

Heavily armed NSW tactical police responded to the incident on Heald Road in Ingleburn, about 50 kms south west of the Sydney CBD, after shots were fired at around 10:45am on Monday.

A 43-year-old man was confirmed dead and two men were taken to Liverpool Hospital for treatment for gunshot wounds when police arrived at the scene.

The Daily Telegraph report the three people shot were brothers. The 43-year-old man killed is Michael 'Mick' Bassal.

Negotiators arrived at the scene on Monday morning and the tactical operation unit established a perimeter around the building after up to five shots were heard coming from the factory.

Detective Inspector Mark Brett told media on Monday afternoon the operation was at "a delicate stage" and advised the public to avoid the area.

One man was also reportedly arrested for hindering police.

A man is led away in handcuffs near the scene of the stand-off