A mining expert explains how to 'gag' a mine to make it safe for bodies to be recovered and gives his view on the second blast.

The families of some of the men trapped in the Pike River mine expressed sorrow rather than anger at a meeting today, John Key says.

World leaders are sending support and sympathy to the families of the men who died at the Pike River coal mine.

Rescue authorities are vowing to recover the bodies of the 29 miners - but admit they don't know when it will happen.

A man has been charged with manslaughter over the death of a woman hit by a car while picnicking with a friend on the roadside north of Wellington last month.

'People find just that extra little bit, they take a deep breath, they will raise the bar…,' Grey District Mayor Tony Kokshoorn says.

The Pike River CEO had to give the worst news possible to families who had looked to him for hope.

Before the service began, 29 candles flickered on a table near the altar surrounded by many unlit candles waiting to be lit by mourners.

'It's the finality of the second explosion that rips at the guts of the country,' John Key tells media.

The first four hours after Friday's Pike River mine blast was the only time rescuers could have entered the mine, a safety expert says.

It was Pike River CEO Peter Whittall who broke the news to the miners' families this afternoon, that their worst fears had been realised.

Families of the 29 Pike River mine victims who perished in today's second blast fell to the floor screaming and were in "absolute despair", when they were told the news.