A police car parked outside the Rotorua police station has been set on fire and destroyed.
Police arrested the suspected arsonist after he lit the fire just after 9pm last night.
Detective Inspector Tim Anderson said the offender had a mental illness.
"It is quite clear the person needs some help," he said.
"Police have arrested the person responsible and have put them before the courts."
Mr Anderson said the parked police car was "pretty much written off" by the fire and the vehicle was undergoing a full inspection for insurance reasons.
The Rotorua Fire Brigade was called to Fenton St at 9.15pm on Monday to deal with the fire.
Fire brigade Senior Station Officer Jim Prescott said when they arrived at the scene, police officers had most of the fire under control.
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