Hastings District Council had not been told a Bridge Pa building consumed by fire on Sunday was being used for accommodation.
A large number of "seasonal workers" were sleeping in the Stock Rd building when it caught fire early Sunday morning.
Hawke's Bay area commander Chris Nicholl said someone had come home early in the morning and tried to extinguish the fire themselves.
Mr Nicholl said fire services were called after the person realised they couldn't contain the fire.
When appliances from Hastings and Napier arrived at the Stock Rd scene just after 2.30am the building was "well involved", but the three appliances on the scene put it out.