Two workers have been killed and another injured in a horror explosion at an underground mine in outback NSW.

Emergency responders were called to the Endeavor Mine near Cobar, in the state’s far west, at about 3.45am on Tuesday following reports two people had been critically injured in a workplace incident.

Police arrived at the scene and were advised that a man aged in his 60s had died in the underground blast.

Two female workers aged in their 20s were transported to the surface, but one was unable to be revived.

Paramedics stabilised the condition of the second woman, who suffered from hearing damage and shock.

She has since been airlifted by the Toll rescue helicopter to Orange Hospital, which is 483km away.

Emergency services remain at the scene with police scheduled to give an update on Tuesday afternoon. 

It’s understood all three workers are locals in the mining town.

Police will prepare a report for the coroner and assist specialists from the NSW Resources Regulator with their investigation.

Cobar Shire mayor Jarrod Marsden described the incident as ‘absolutely tragic’.

‘The most valuable thing in a mine are the miners, and two families won’t see their loved ones again,’ he said.

NSW Natural Resources Minister Courtney Houssos and Premier Chris Minns extended their deepest condolences to the victims’ families, friends and colleagues.

‘This is a heartbreaking day for the Cobar community, and will be felt across the entire mining industry,’ a joint statement read.

‘The number one priority in any mine must be safety. Everyone who goes to work has the right to come home.

‘While safety protocols and procedures have greatly improved in mining, these deaths are a sobering reminder of why we need to always remain vigilant to protect workers.’

Daily Mail has contacted the mine’s operator Polymetals and the NSW Resources Regulator for comment.

Located 40km north of Cobar, Endeavor is a major underground silver, zinc, and lead mine operated by Polymetals.

The project is described on its website as the second-largest mine in Australia’s richest polymetallic region known, as the Cobar Basin.

The mine first began operations in 1982.

Operations ceased in 2020 when the site was placed in ‘care and maintenance’ but remained ‘operationally ready’.

Polymetals acquired the site from CBH Resources last year.

‘We can now get on with what the company has done best for many years; namely, the cost-efficient development, management and operation of mines within Australia and particularly within the very familiar and fertile polymetallic Cobar Basin,’ Polymetals executive chairman Dave Sproule said at the time.

Mining operations resumed in June, with the first cargo of zinc scheduled to be exported to South Korea this month, according to a recent Polymetals update.

Anyone with information about Tuesday’s underground mine explosion is urged to call Crime Stoppers on 1800 333 000.