Counties Manukau fire safety officers are investigating the blaze of a large house near Mangatawhiri this morning.

The occupants of the house were home at the time but escaped unscathed, Northern fire communications shift manager Scott Osmond said.

Firefighters were called to the Pinnacle Hill Rd property, off State Highway 2, just before 4.30am today.

Brigades from Mercer, Tuakau and Pukekohe attended the fire.