Fire and Emergency New Zealand southern communications shift manager Lyn Crosson said police and firefighters were called to an address in Pearson Rd, near Cromwell, about 1am on Saturday, after reports of a garage fire.
But flames had moved from the attached garage into the main house.
Initially, two fire engines from Cromwell and one tanker from Dunstan were called but the fire was so "well involved" that a fire engine each from Clyde and Alexandra were also called in.
Speaking at the scene later on Saturday, Cromwell Chief Fire Officer Steve Shaw said people living on rural properties should be aware of where their closest water source is in case of fire.
"In this instance, we were fortunate to have a good source with a pond."
Fenz fire risk management officer Mark Bredenbeck said people needed to make sure they had working smoke alarms.
"That did save some people’s lives last night."
Fire staff were still investigating the cause but it did not look to be suspicious.
