A gunman who engaged police in an hours-long standoff at a Sydney factory has shot himself dead, say authorities.

His death came shortly after three people were seen leaving the building and entering a police vehicle. It has not been confirmed they were hostages. The gunman had opened fire at the industrial unit on Monday morning, killing a man and injuring two others.

Police quickly surrounded the factory, located in the industrial suburb of Ingleburn in the city’s southwest. Authorities have named the gunman as Wayne Williams. His motives and relationship to those in the factory remain unclear, but the Sydney Morning Herald said Williams was a member of a motorcycle gang and that the man who was shot dead was connected to another motorcycle club.

The two injured men were transported to Liverpool Hospital and were in a stable condition. One of the men underwent emergency surgery, while the second suffered superficial wounds to his lower body. Reports from media at the scene said the man was believed to be using an automatic rifle.

Photographs show heavily armed police surrounding the Inline National Signage factory, and what appears to be a body underneath a white sheet on the sidewalk. A man was arrested at the scene, but police said he was detained for “hindering” the investigation.