'Indescribable': A tourist documents hell unfolding on Whakaari/White Island

San Francisco tourist Michael Schade shot footage from the edge of Whakaari/White Island's main crater half an hour before it erupted. Image / Michael Schade

Half an hour before Whakaari/White Island erupted, a tour group was standing at the edge of the main crater, peering into its sulphurous depths.

Among them were San Francisco tourist Michael Schade and his family. Panoramic footage shot from Schade's phone shows steam slowly drifting into an otherwise cloudless sky, the crater's edge cake in yellow, wind rumbling on his microphone.

The last photo Schade shot while on the island was timestamped 1:49pm.

Twenty minutes later, as the family waited onboard for their boat to leave, the volcano erupted, spewing steam and ash into the air.

My god, White Island volcano in New Zealand erupted today for first time since 2001. My family and I had gotten off it 20 minutes before, were waiting at our boat about to leave when we saw it. Boat ride home tending to people our boat rescued was indescribable. #whiteisland pic.twitter.com/QJwWi12Tvt

— Michael Schade (@sch) December 9, 2019

Schade's first photos of the eruption was taken at 2.12pm, a minute after it began, showing thick grey clouds boiling into the sky.

Schade took his first photo of the eruption a minute after it began at 2.11pm. Photo / Michael Schade

It's now been confirmed there were two eruptions in quick succession.

Afterwards, the island is a different world. Ash blankets everything in a grey carpet up to half a metre thick, including a helicopter.

A helicopter that appears to have its rotor blades broken sits among thick drifts of ash. Photo / Michael Schade

Schade's tour boat heads back in to the island, where a group of people can be seen stranded on a jetty, coated in ash.

There were two groups of tourists on the island; one was able to escape. A second group were standing close to where the eruption occurred.

Around 10 people stand on a jetty waiting to be rescued by White Island Tours crew. Photo / Michael Schade

Photos Schade took at 2.24pm show rescuers from White Island Tours scrambling onto the jetty and helping people into their dinghy. The weighed-down dinghy heads back to the main tour boat, the tour guides' arms around the survivors.

White Island Tours crew members scramble aboard the jetty to help survivors get off the island. Photo / Michael Schade

Schade tweeted his "endless gratitude" to the tour crew for stepping up as first responders.

That boat ride back to the mainland - tending to those rescued - was "indescribable", Schade tweeted.

He was "praying for them and their recovery".

A dinghy full of survivors with White Island Tours crew members heads back to the main tour boat. Photo / Michael Schade

"[The] woman my mom tended to was in critical condition but seemed strong by the end," he wrote.

"The helicopters on the island looked destroyed."

At a press conference this morning, Prime Minister Jacinda Ardern confirmed there had been two groups on the island - one that had been evacuated, and a second that was close to the eruption.

Of the 47 people on the island at the time of the eruption, 39 have come off the island.

Five of those people have died, while 31 are still in hospital and three have been discharged.

The remaining eight are still missing and presumed to have died. Aerial reconnaissance showed there was no sign of life remaining on the island this morning.