Sydney CBD Evacuated After Major Gas Leak, Motorists Warned To Avoid Area

Parts of the city have been evacuated and the public is being told to avoid the area.

A major gas leak has caused parts of the Sydney CBD to be evacuated and Martin Place train station, with buses diverted around the area.

A ruptured gas line has been identified as the cause of the leak, which had been spewing a steady flow of gas since about 10.30pm on Friday.

"Workmen, they breached a high pressure gas main, a 200ml gas main, quite a large one," Superintendent Paul Johnstone from Fire and Rescue NSW said.

"Fire rescue crews were alerted to it and the first arriving crews found a large volume really roaring out of the gas main."

A 200m exclusion zone was established, while six firetrucks and hazmat specialists attended the scene overnight.

Several streets around Castlereagh and Hunter streets have been evacuated, while Elizabeth Street and Phillip Street have been closed to the public.

Macquarie Street is closed between Hunter Street and James Road until further notice.

Locals spoke of hearing a "torrential sound" in the area, believing it at first to be a storm.

"As we left the building, the sound was deafening, as if there were thousands of industrial fans right in front of you," Eliott Oliver told 9news.

"A lone police officer was standing outside and looked really surprised, telling us to get out of the area immediately."

Image: AAP

A 200-metre evacuation zone will be in place until the a permanent solution to the gas leak is found.

"Diversions are still in place around Sydney CBD due to reports of a major gas leak," police said on Saturday morning.

"If you are planning to come into the city this morning, motorists are urged to check livetraffic.com for alternative routes. Bus and rail service are also affected."

All trains will continue to run on the City Circular and Eastern Suburbs line but won't stop at Martin Place.

Motorists and commuters are warned to avoid the area as authorities work to patch the leak.

With AAP.

Photo: Catherine Cuask / Twitter.