Two men have died 125 metres below the surface after falling down a hole, known as a stope, in a mine in outback Queensland.
This is what we know about the situation so far.
The Dugald River zinc underground mine is about 70 kilometres north-west of Cloncurry in the state's north-west.
On Wednesday morning, the light vehicle the men had been operating plummeted into a 25m hole inside the stope, which was about 100m below ground.
A drilling rig also fell into the hole, but the operator of the rig was able to escape and was later rescued.
The men, identified as Dylan Langridge and Trevor Davis, were employed by MMG's contract partner, Barminco.
What was done to reach them?
By Thursday afternoon, crews had reached the site of the fallen utility and were using machinery to remove rubble from around the vehicle.
Hours later, Mr Langridge and Mr Davis were confirmed to have died.
Perenti managing director Mark Norwell said it was a "devastating outcome".
"I want to extend my deepest sympathies and condolences to the families, friends, colleagues and loved ones of Trevor and Dylan, both of whom should have come home safely from work," he said.
Drones were used to canvas the stope and give authorities a better understanding of what was below the surface.
Speaking on the evening of incident, Dugald River general manager Tim Akroyd said it was "terrible, tragic".
"Our absolute priority is finding the two people who are currently missing," he said.
Mr Akroyd said data captured from the drone footage had enabled the rescue team to access the vehicle from below.
"We're using advanced drone technology to understand the specific conditions of the area, to enable us to ensure the safety of our rescue teams," he said.
"The drone is fitted with technology that can capture video data, data regarding the size of the cavity of where the light vehicle is located."
What is a stope?
A stope is a large hole where ore is extracted. Previous accidents where people have fallen into stopes have been fatal.
Since 1991, four people have died going over the edge into a stope in Queensland.
Pekka Tuppurainen was driving a loader when it fell into a 20-metre hole at Xstrata's George Fisher mine near Mt Isa in 2009.
A coronial inquest found it was an accident. It heard Xstrata had reviewed its backfilling procedure — designed to stop a vehicle going over the edge into a stope — prior to Mr Tuppurainen's death, and had been considering using steel logs. The inquest found steel logs could have prevented the tragedy.
Professor David Cliff is a research fellow at the University of Queensland's Minerals Industry Safety and Health Centre, which is partly funded by the mining industry.
He said it was "very unusual" for someone to fall down a stope, and that these type of accidents were preventable, and it was surprising they still happened.
"In underground mines, the most common fatality is a failure of the ground above people or beside people, falling onto people. A stope is like a cave, so rocks or parts of the cave can fall on people," he said.
"There are a range of causes but this is very unusual for people to fall [into a stope]."
How safe are Australian mines?
A 2019 study found the Queensland mining industry has the third-highest work-related fatality by industry rate.
"The committee observed a theme that has permeated multiple government inquiries into safety in the mining sector," chair of the transport and resources parliamentary committee Shane King said.
"Companies speak loudly about their overriding commitment to safety, while individual workers find themselves having to 'speak up for safety', sometimes at significant personal cost to themselves, due to the perceived threat of reprisal.
"Risk-based legislation absolutely plays a role in upholding mine safety, but only truly tripartite and ongoing collaboration and information sharing between industry, workers, workers' representatives, and the regulator will guarantee it."
Australia's mines are "amongst the safest in the world", Professor Cliff said.
"People aren't falling down holes in mines all the time. There is a total of five fatalities in Australian mining in the last 12 months around the whole country and they are from a range of mechanisms.
"People shouldn't think that this sort of thing happens often — it doesn't."
But mines "are still not as safe as they should be", he said.
And he said there was "no logical reason" why they should not be safe to work in.
"Fundamentally it is surprising that we still have fatalities, but then we still have fatalities in general industry as well.
"And that's also surprising because we're [in the] 21st century, with high-technology, sophisticated machines, highly educated people, this should not be happening."
