The New Zealand military will deploy to White Island at first light in an attempt to bring eight bodies home to their desperate families – despite a serious risk of the volcano erupting again.

Eight specialist military personnel will land on the island on Friday morning local time (Thursday evening UK) in an operation that is expected to last several hours, and involves multiple risk factors including the Island’s heightened seismic activity, the weather, and conditions on the ground.

Six of the eight bodies have already been located, Mike Clements, the deputy commissioner of national operations said, but the whereabouts of the other two were unknown. Military personnel would search for them, he said, but in a limited capacity as the risks were so high.

An elder from the Maori tribe of Ngati Awa offered a karakia (prayer) for the retrieval mission on Thursday evening, and a large contingent of domestic and international media wished the commissioner “good luck”, after he admitted he was “very worried” about the risks involved in the retrieval mission, with his greatest fear being the volcano’s unpredictability.

Clements said police had decided to go with the snatch and grab option – essentially, to get on and off the island as quickly as possible – despite the numerous risks involved.

GNS volcanologists would be stationed in Whakatāne providing real-time monitoring for personnel on the ground, and contingency plans were in place in case the island erupted again, with the military kitted out with protective clothing and breathing apparatus for the mission.

Clements said he had no knowledge of a similar mission being enacted anywhere in the world.

“The risk I spoke about this morning has not passed. We do not expect anything to change overnight or tomorrow in regards to the risk,” Clements said.

“A lot has to go right for us tomorrow to make this work. There is no zero-risk option in regard to the plan but we have carefully considered it … Fingers crossed.”

GNS volcanologist Graham Leonard said the volcano’s state of unrest had increased since Monday’s eruption and there was now a 50-60% chance of another eruption in the next 24 hours. Despite this, police were determined to make an attempt to land on the island.

Clements said police had been facing increasing pressure from families to retrieve the bodies, as there was a very real chance another eruption could mean they would be lost forever.

On the ground in Whakatāne, residents expressed mixed reactions to the police plan.

Wayne Winiata, 69, a local osteopath, said it was odd that police had waited all week to retrieve the bodies, and then decided to go when the risk was highest.

“It will be nice to have them back, but the safety thing for the people that are actually alive, that’s what I am worried about,” said Winiata. “Are we rushing? That’s the question. For something that we can’t change. Those people are already gone.”

Hiko Merito, 25, said she “desperately wanted everyone to come home” and criticised the police for waiting until Friday. “I hope it doesn’t upset White Island too much to blow again,” said Merito, who lost a friend in the disaster.

“They shouldn’t have gone on there in the first place. It’s good to watch her from afar, not to actually step on sacred ground.”

The plan for the police operation came as it emerged two more people had died from injuries sustained during the eruption. A total of 16 people are believed to have died, with 14 confirmed deaths of Australian citizens or permanent residents. A New Zealander, tour guide Hayden Marshall-Inman, has also died.

If the volcano remained in a heightened state of activity for days or weeks, Clements acknowledged police had to consider retrieving the bodies anyway, even if the rushed rescue would potentially destroy some evidence.

“There won’t be a person in the room who has more passion about going onto that island than police staff – I give that commitment to this community, to those whanau [family], I know everybody is watching,” Clements said.