Emergency services are at the Tahmoor coal mine, where two miners are trapped underground.
A spokeswoman for NSW Police said rescuers were called to the site just before 5pm Wednesday.
She said the two men are not injured, and rescue efforts were underway to retrieve them, as at 6.30pm.
Picton Fire and Rescue said on Facebook that a crew was on site with Liverpool and Mittagong Fire Rescue crews.
“Two persons are stuck in a broken down lift underground,” the post said.
“No injuries at this time.”
The Advertiser understands the emergency centres around a broken lift. The cage-style lift operates via a winding mechanism.
Fire and Rescue NSW Superintendant Graham Jarrett said the men were trapped about 160 metres underground.
“They’re OK, there’s plenty of ventilation for them,” he said.
The trapped men have been able to communicate with their rescuers by radio, the Mercury understands.
Four fire rescue crews are on site, including specialist rescue and technical rescue units from Liverpool and Picton.
“We’re getting out kit out there, working with the mine people and doing our risk assessment and making sure everything’s right before we go ahead with the rescue,” Supt Jarrett said.
“At this point, they’re setting up a secondary crane system to assist in the removal of the cart.”
In a statement just issued, a spokesman for SIMEC Mining said the emergency was the result of a mechanical breakdown.
“SIMEC Mining is working to ensure the safety of two of its employees who have been unable to exit a mine shaft due to a mechanical breakdown.
“The employees are uninjured, and their families have been contacted and are being regularly updated on their status and the progress of the response.
“As always, the safety of our employees is of utmost importance, and we are working in conjunction with external emergency services to develop plans to bring the two employees safely to the surface.
The spokesman said the lift came to a halt at 3pm as it was carrying the men from the bottom of the pit to the surface.
“The lift … came to rest more than 150 metres from the surface when its protection systems engaged,” he said.
“The lift has been isolated both electrically and mechanically and has been stabilised. Two‐way communications are in place between the lift and the surface, and the two mine employees are assisting with the response.
“Investigation of the cause of the incident will follow once the mine employees are safely brought to the surface.”