At least 27 victims of the New Zealand volcano suffered more than 71% body surface burns as it's feared the death toll will rise.
Peter Watson, the government's chief medical officer, said some of the victims could succumb to their wounds after the eruption off White Island yesterday.
Burns units across the South Pacific nation of 4.5 million are full to capacity, he added.
Police today confirmed a sixth person had died after the tragedy.
A spokesman said this morning: "Police can confirm a further person has died following the eruption on Whakaari / White Island, bringing the official toll to six.
"The person was earlier being treated at Middlemore Hospital.
"Police remain focused on supporting families at this terrible time."
Fearing the volcano could erupt again, search parties were unable to set foot on White Island.
Prime Minister Jacinda Ardern said reconnaissance flights showed no signs of life on the ash covered island, and police doubted whether any survivors would be found. "The scale of this tragedy is devastating," Ardern said in parliament.
"To those who have lost or are missing family and friends, we share in your grief and sorrow and we are devastated."
Police said 47 people were on the uninhabited island, a popular sightseeing excursion for tourists, at the time of the eruption.
Twenty-four came from Australia, nine from the United States, five from New Zealand, four from Germany, two each from China and the Britain and one from Malaysia.
"I would strongly suggest that there is no one that has survived on the island," police Deputy Commissioner John Tims said of the eight people still missing.
