Police want to speak to anyone who saw a red or maroon car knock over a power pole in Kowhai St at the weekend.
Senior Sergeant Shayne Wainhouse said a car struck the pole, knocking it over, but had left the scene by the time emergency services arrived.
The crash happened about 7.30pm on Sunday in Castlecliff.
He said the vehicle was "described as a red or maroon car".
"Police would like to speak with witnesses to the crash," he said.
Whanganui Fire Senior Station Officer Jemal Weston said a power authority was needed to turn off the power to the pole.
Firefighters were also called out on Sunday to a grass fire at Mosston Park in Castlecliff.
Mr Weston said the fire in Rogers St measured about 50mx50m.