Two senior medical clinicians spent about half an hour on Whakaari/White Island yesterday afternoon before concluding there was no one left who could be rescued.
Intensive care paramedic Rusty Clark was on board the Westpac 2 rescue helicopter from Auckland, which was sent out at 2.45pm yesterday.
The chopper arrived at Whakatane Airfield where a staging area was set up for a mass casualty incident.
From Whakatane Airfield the crew were sent to the island, where they were tasked with winching a critically injured patient off a boat.
During a flyover the crew assessed the risk of further eruptions and whether it was safe for the crew to land.
"We made contact with the vessel and by that stage they were about 7 miles off the coast of Whakatane so we deemed it appropriate for them to continue to shore," Clark said.
They then landed on the volcano, with two clinicians - an experienced intensive care paramedic and the medical director for St John - leaving the chopper to look around.
Footage shot at the scene shows the pair ducking to escape the wash of the rotor blades, which stirred up clouds of ash.
"They ... spent some time in a safe area, they tried to do an assessment and see if they could find anybody else," Clark said.
"If there were any people that we could bring off then we would formulate a plan, we were in direct comms with them. We basically stayed in the parameters of the island within a safe distance, and we could then go and extract them if we needed to."
The pair were on the island for between 30 and 40 minutes, he estimated, but by the end of that time it was clear that "everybody that could come off was already off the island."
Clark said the pair had "possibly" encountered other people who had not survived.
They then returned to the airfield where they were tasked with taking patients to predetermined hospitals.
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Rescue crews go into search and rescue jobs "absolutely" hoping to find survivors, he said.
"That's why we do this job - when things go bad we're often the ones that have some more capability to get to people where it might be a bit difficult. When we get to retrieve survivors it's a really good feeling and it's great."
However despite being unable to rescue anyone on Monday, crew members were coping OK, Clark said.
"The collective experience of all the crews involved is quite vast. Although ... it was a big incident, it's not something that was new to us."
He praised the overall emergency response.
"As a whole from what I saw I think the job was managed especially well, given the location and the difficulties that they faced, particularly with the local community.
"I think everybody did very well and they should be very proud of themselves."