The explosion that left 29 miners missing in New Zealand was a series of bangs that pelted debris and made it a struggle to breathe, said a coal cutter who lost consciousness but eventually walked out of the tunnel with minor injuries.
Toxic gases after Friday's explosion are still preventing rescuers from entering the mine, and evidence of heat underground was concerning officials, who feared there could be another blast.
"Something is happening underground, but what it is we don't know," said Peter Whittall, chief executive of Pike River Mine.
Fresh air was being pumped down an open air line, but gas levels were still fluctuating so much that waiting rescue teams were forbidden to enter the mine near Atarau on South Island.
A six-inch-wide hole was being drilled from the mountain above down 500 feet to the mine to assess air quality and to lower listening devices.
The missing miners have not been heard from since the blast but officials insist the search for them is a rescue operation.
Survivor Russell Smith was an hour late for work on Friday and so was not deep in the mine with those missing. He and fellow survivor Daniel Rockhouse walked out of the tunnel more than an hour after the explosion.
Pete Rodger, 40, from Perthshire, and Malcolm Campbell, 25, originally from St Andrews, Fife, are among the 29 miners missing after a fireball ripped through the mine.
Scotland's First Minister Alex Salmond told BBC Reporting Scotland: "For countries with mining communities themselves, but I think for everyone, this has a particular resonance. We are concerned obviously for the fate of all 29 of the miners who are trapped.
"But the fact that two Scots are among them and two Scottish families have that immediate concern makes that all the more immediate for people across Scotland. But there's no more we can do than send our best wishes for rescue."
Read More
MORE ABOUT