Update 4.35 pm: Power was restored to 531 properties in Mount Maunganui at 4.17pm after a tree branch landed on power lines on Concord Ave at 3.45pm today, said a PowerCo spokesperson. 

"When overgrown, trees can interfere with power lines, cause outages and make it difficult for our crews to restore power. Trees in lines also pose a fire risk."

The spokesperson said property owners are legally required to keep trees a minimum safe distance away from overhead lines under the Electricity (Hazards from Trees) Regulations.

"If your tree grows too close, you must get it trimmed by an approved contractor."

People can find out more about the regulations here: https://www.powerco.co.nz/safety/tree-safety-near-power-lines

Initial report, 4.02 pm: A power outage has hit 531 properties in Mount Maunganui after a 'massive bang' was reported.

A caller to 0800SUNLIVE from Mount Maunganui said, "We just heard this massive bang and then our power went out".

According to the PowerCo website, 531 properties in Mount Maunganui are experiencing a power outage.