American teenage brothers killed when New Zealand volcano erupts – and their parents are missing

Two US-born teenage brothers have been identified as victims of New Zealand's volcanic eruption, while their parents remain missing.

Matthew Hollander, 13, and Berend Hollander, 16, died in hospital from injuries sustained in Monday afternoon's explosion at White Island, the boys' family members confirmed in a statement obtained by PEOPLE.

The boys' parents, Martin Hollander, 48, and Barbara Hollander, 50, are still missing, according to the Chicago Tribune.

“We are absolutely heartbroken by this loss. Ben and Matthew are wonderfully kind and spirited boys who have lived short but very full lives,” the statement read. “They loved [their school] and all their friends, as well as the sporting and outdoor Australian lifestyle they adopted when they left the United States six years ago. They had a positive and lasting impact on the paths of everyone they crossed paths with.

Matthew and Berend, called Ben, were born in the Chicago area, although the family later moved to Martin's native Australia. Tribune reported.

“They were one big family,” Chicago neighbor Jeff Richmond told the outlet. “The boys were very nice, always active and always outside. They were very nice people.

The boys attended Knox Grammar School in suburban Sydney and the school's principal, Scott James, confirmed their deaths in a letter to parents obtained by PEOPLE.

Both Matthew and Ben were very involved in school, and both played various sports and participated in the Australian Army Cadets, James wrote.

“Matthew had a close circle of friends and was popular among his peers. He was always enthusiastic about life and was actively involved in school and year group activities,” the letter read. “Ben’s engaging smile and quirky sense of humor made him a good companion to his close group of friends and a welcome member of every class.”

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Dad Martin's LinkedIn page lists him as an investment director at Wipunen Incrementum Capital in Sydney.

The boys are among eight confirmed victims of the White Island eruption, although the death toll is suspected at 16 as eight people remain missing on the island.

Australian Julie Richards, 47, and her daughter Jessica, 20, were also confirmed to have died in the explosion by a family spokesperson.

A State Department official confirms to PEOPLE that U.S. citizens are among those injured and missing following the incident, but that identification of the victims is still underway.

The US Embassy in New Zealand said in a statement that it was aware of “victims of US citizens”, although the number remains unclear. There were nine American citizens on the island when the volcano erupted.

Police said Thursday they have developed a plan to recover the bodies still on the island, although this is subject to various risks, including weather conditions.

“A lot needs to happen tomorrow for this to work,” police said in a statement. “There is no zero risk option when it comes to this plan, but we have considered it carefully. We don't expect the risk to change tonight or tomorrow, but we have planned for it.

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At least 28 patients are still being treated at six New Zealand hospitals, and 23 are in critical condition, officials said.

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Geoff Hopkins, who was leaving the island by boat after a day of exploring with his daughter, said his boat turned around to help the victims, many of whom suffered severe burns.

“There were 23 people who had their lives in our hands,” said his daughter Lillani. Thing. “It was probably the longest two hours of my life.”

Forty-seven people were visiting the island when the volcano erupted, and more than three dozen were traveling aboard Royal Caribbean's Ovation of the Seas cruise ship.