The families of the 29 men who died in the Pike River Coal mine disaster are waiting to know when their men can be found and brought home.
The West Coast town of Greymouth has been mourning on Thursday, after a second explosion at the mine on Wednesday extinguished hope that the men, who had trapped since Friday, could still be alive.
Pike River Coal met with the families on Thursday and says it has promised it will retrieve the lost men.
But it may be days or even weeks before the mine's environment is stabilised and the bodies can be recovered, say police.
At a media briefing in Greymouth on Thursday, the officer in charge of the recovery operation, Superintendent Gary Knowles, said air samples were still being taken and it was still extremely risky to send people underground.
Pike River Coal chief executive Peter Whittall said Wednesday's explosion did not ignite all the gas in the mine, so there was a possibility of another blast. He told a news conference on Thursday that there had been no change in gas levels underground.
Mr Whittall said it could take up to a week before anyone could enter the mine.
He said footage from the second blast was given to police on Thursday morning. He said the company recommended to police that they not make it public, but the decision would be theirs.
Mr Knowles said mining experts, including from Australia, were putting together recovery options. The first action was to neutralise the tunnel environment and make it safe for people to enter.
Mr Knowles said he was at the mine when the second explosion happened on Wednesday afternoon. He said he saw "hard men" crying at the reality that they could have been down there if they had gone through with a rescue operation.
He could "see the shock" on their faces after the second explosion. "They realised that had they been underground they would have been dead," he said.
Mr Knowles said the families were "in a state of shock".
"These people are grieving," he said.
Two Defence Force robots equipped with cameras were in the mine at the time of the second explosion, but he said "that's the least of my worries".
Prime Minister John Key said in Greymouth on Thursday that Australian Prime Minister Julia Gillard had offered equipment that would make the mine safe so the bodies could be recovered.
No decision made yet about recovery
Earlier, Assistant Police Commissioner Grant Nicholls said no decision had been made as to when and how the bodies of the miners would be recovered.
Mr Nicholls said there were many issues to be considered first. Before the bodies could be recovered, the heat source and gases in the mine needed to be identified, and the risk of another explosion assessed.
Mr Nicholls said various techniques to make the mine safer are also being investigated.
Recovery important, says mayor
Earlier, Grey District Mayor Tony Kokshoorn said it was important the miners' bodies were retrieved.
He said the community was now focusing on uniting to make life as easy as it could be for the affected families.
Mr Kokshoorn said the priority was to bring out the bodies and authorities must pull out every stop to achieve that.
Labour Party leader Phil Goff also said every effort must be made to recover the miners' bodies for the sake of their relatives. Mr Goff said the families deserved to be able to lay their men to rest with dignity.