WELLINGTON, New Zealand, Nov. 26 (UPI) -- A third explosion rocked the Pike River coal mine in New Zealand Friday, a week after the first blast trapped 29 miners now believed dead, officials said.
Pike River Chairman John Dow said the latest explosion at the underground was smaller than the first two, which occurred last Friday and Wednesday, the Wellington Dominion Post reported.
"I've just been talking to Inspector John Canning and he confirmed that we've had a third explosion at 3.39 p.m.," Dow said. "It lasted about 20 seconds and was smaller in magnitude [than previous ones].
"There was nobody at the portal -- there was nobody at the site [at the time]."
The mining company executive said the blast, which occurred as New Zealand was observing a moment of silence for the miners, would not "mean a step back at all" in efforts to recover the miners' bodies but no one is estimating how long it will be before that happens, the newspaper said.
The company needs to assess how much damage had occurred underground, Dow said. A jet engine is to be in place by Monday to begin sucking oxygen out of the mine shaft in an attempt to make it safe to enter.
"Clearly we won't be a coal mine for a while," he said.
There will be at least four investigations into the deadly accident, Police Minister Judith Collins said.
The rescue team at the mine says there was no opportunity to enter the mine after the first explosion. Talk of a window of opportunity right after that first blast was inaccurate, Trevor Watts from New Zealand Mines Rescue said, since methane immediately began accumulating again.
The initial explosion ruptured an underground gas drainage line and it immediately began spewing 200 gallons per second of methane into the mine, Watts told TVNZ.
Miners were "chomping at the bit" to get underground to help their colleagues, Watts said, but the risk was too great.
"If we had sent them in we would have killed between 12 and 18 mines rescue members," he said.
Rescue workers are still united in their desire to go in and retrieve the bodies, Watts said.
"We will minimize the risk as much as we possibly can, but our men are still going to be faced with hostile conditions," he said.
"We've got to prepare ourselves for a tough and difficult task."