The "exceptionally dangerous" ordeal began in the early hours of Tuesday, when a group of men, one armed with a gun, allegedly burst into a home at Bringelly in Sydney's south-west.

The men assaulted the 61-year-old occupant before forcing another man, 37, into a car outside.

Emergency services were called about 3am, with police establishing a crime scene and paramedics treating the older man for minor injuries.

Detectives and police negotiators were then sent to an industrial warehouse at Marigold Street, Revesby where the abducted man was being held.

After negotiations, the 37-year-old was eventually released into policy custody and taken to hospital with non-life-threatening injuries to his head and face.

However the saga wasn't over, with the alleged offenders then setting the warehouse ablaze.

Fire and Rescue worked to control the fire as police nabbed the eleven men allegedly behind the kidnapping.

Three men were arrested after showing up to the property during the operation, and another eight taken into custody when it concluded.

Four of the men are receiving treatment in hospital. The others were taken to Liverpool and Bankstown police stations where they are awaiting charges.

Detective Superintendent Andrew Koutsoufis told reporters the abducted man is lucky to be alive.

"The incident was exceptionally dangerous and could have been even more severe, or even fatal," he said.

"The level of violence towards the alleged victim was quite severe."

Inquiries are continuing, but police believe the incident is related to organised bikie crime.

Australian Associated Press