The gunman at the centre of a six-hour siege at a Sydney industrial unit has died from a self-inflicted gunshot wound hours after a 43-year-old man was shot dead, police say.
Heavily armed police had surrounded Inline Signage on Heald Road at Ingleburn after a gunman opened fire about 10:45am (12.45pm local time), killing a 43-year-old man and wounding two others.
This afternoon three people were seen being placed into a police vehicle after walking out of the building.
Police would not confirm if they had been directly threatened by the gunman.
The tactical operations unit, negotiators and paramedics were on the scene, but the police presence has reduced in the past hour.
One man was arrested at the scene earlier for allegedly hindering police.
One of the injured men was shot in the leg, while the other was shot in the shoulder. Both were taken to Liverpool Hospital.
"On arrival police found three males, one deceased and two others with gunshot wounds," Detective Inspector Mark Brett from Macquarie Fields Local Area Command told a media conference.
"Two men with gunshot wounds have been conveyed to Liverpool Hospital."
Police said one of the men had emergency surgery, while the other had superficial wounds to the lower part of his body.
A Liverpool Hospital spokeswoman said both men were now in a stable condition.
The immediate area around the signage business has been evacuated and members of the public are being warned to stay away.
Police said they do not believe the shooting is terrorism related.
Witnesses from nearby businesses said they heard five gunshots ring out, and one person said police "told us not to go near windows".
A man who works in the building complex where the shooting took place said he heard a loud bang, which he later realised was a gunshot.
He said police then evacuated his office and others in the building.
The man said he was sheltering with about 30 other people at a nearby business under police protection.
Rogan Burns, who works at an entertainment agency about 50 metres from where the shootings took place, said the whole area was in lockdown.
"My colleague actually left to go and get the boss a cake for his birthday and the police came screaming in in the vehicles and just told everyone to get back inside their factories," he said.