A 10-year-old boy has died after yesterday's fire in Hastings.
He died in Hawke's Bay Hospital early this morning.
Another child remains in a stable condition in hospital.
Police are investigating the fire, which is being treated as suspicious.
Two children and three adults were rushed to hospital after the large fire in Saint Leonards, Hastings yesterday afternoon.
A nearby restaurant owner said he helped a severely burned child.
The man described wrapping a child in food wrap and pouring cold water on them - something he said he would never want to do again.
Fire assistant area manager Nigel Hall said firefighters were called about 2.50pm to the blaze, which was "well involved" by the time they arrived.
Hall said it was in a derelict building not in use for anything.
"We managed to get the fire under control quite quickly but unfortunately there were some casualties, with two people taken to hospital with burns and a further [three] with smoke inhalation."
Anyone who saw any unusual activity near the property on Heretaunga St West is being urged to called Hastings Police on (06) 873 0500 or Crimestoppers anonymously on 0800 555 111.