A man has been arrested after going on a rampage with an axe at the BNZ bank in Whangamata.

And a member of the public is being hailed a "hero" after he barricaded him inside and waited for police to arrive.

Whangamata Police Sergeant Vince Ranger said officers were called to the BNZ bank on Port Rd shortly after 10am.

"Officers arrived to find a number of windows at the bank had been smashed and a counter damaged by a man armed with what was described as an axe.

"No-one was injured in the attack and it does not appear that the offender's intent was to rob the premises."

A 53-year-old local man was arrested at the scene and is being questioned by police.

Three bank staff escaped out the front door and a member of the public used a power cord to tie the doors together, trapping the attacker inside, BNZ external communications manager Emily Davies said.

A fourth staff member was stuck in the bank with the axe-wielding man for a short time, but got out before police arrived.

Ms Davies said the man who blocked the doors was being hailed as a hero.

A "significant" amount of damage had been caused by the man, who didn't target any of the staff or customers in his attack.

A Whangamata woman said she was with her partner opposite the bank at about 10.15am when she noticed the windows were being smashed from the inside out.

Shoppers and staff from nearby shops gathered outside to see what was going on.

Police arrived and entered the bank carrying a "huge gun," she said.

It was not a hostage situation, police north communications shift commander Earle McIntosh said.

"I don't know where he has come from or whether he was a disgruntled customer and we have no idea what his motive was - we are trying to establish that now."

The bank was closed as it was currently a crime scene. 

Staff were receiving support from both the bank and police.

- © Fairfax NZ News