Lavinia Sykes, who chairs the Ngati Kahu Te Kohanga Reo Trust, said the fire was devastating.
The kohanga had just moved from premises at Waitaruke, near Kaeo, and could not return there, that building having been condemned.
One of the teachers said everyone had been looking forward to the new beginning.
"The old [building] was pakaru," she said, "and moving into this place was like winning Lotto."
While the centre had not yet been licensed or officially opened, all the kohanga property, from computers and a lounge suite to the children's taonga, had been moved in. All had been destroyed.
"Everything was going so smoothly, and now this," Ms Sykes said.
The only good news for the kohunga was that a nearby business had offered premises for it to use, but that still left the problem of replacing all the equipment that had been lost.