Coromandel police officers are baffled as to why anyone would want to set fire to their small station.
Senior Constable John Morrissey, who lives behind the two-officer police station on Kapanga Road, was alerted to the fire by a neighbour about 3.30am on Good Friday.
He extinguished the blaze with a hose before fire trucks arrived.
Senior specialist fire investigator Todd O'Donoghue said the blaze was arson.
"I've ruled out any other possible causes so it's now a police investigation to determine who deliberately lit it."
It did not appear an accelerant had been used, he said.
The fire had caused damage to an outside wall and to the underneath of the floor, destroying phone lines and computer wires, Mr Morrissey said.
These had been replaced and the station was up and running again.
Mr Morrissey had no idea why anyone would want to do such a thing.
"I guess it's one of the cards that's in the deck - it happens from time to time around the country - and now, unfortunately, it was my turn.
"It's pretty sad event when something like this happens, it has an impact on the whole community really."
The Thames CIB is investigating.
NZPA