At least one person has been killed and two people were injured in a shooting incident in Sydney.

The shooting happened at a factory on Heald Road, Ingleburn, about 10.45am on Monday, the Sydney Morning Herald reported.

Police who responded to emergency calls found at the scene of the incident three people with gunshot wounds. While one of them was confirmed dead later, th others are being treated in hospital.

There are unconfirmed reports that three people are still inside the building with the suspected shooter.

At least three ambulances have been cited at the scene while a large posse of policemen have surrounded the building where the shooter is still believe to be holed up.

Witnesses said they heard as many as five shots. A motive for the shooting could not be established as yet.