Staring down the barrel of a sawn-off rifle, Gavin Benney put his hands up.
"No worries, you go," the former policeman said.
The two masked robbers ran off, and Benney waited a few seconds before giving chase.
He stopped when the pair, believed to have robbed the ANZ bank on the corner of Bank St and Rust Ave in central Whangarei, got into a red Holden Commodore in Second Ave.
About 11.30am yesterday, two masked men had entered the bank and demanded cash, before fleeing.
Nine bank staff and two customers were present at the time but none were injured.
Benney, a former police officer who is now a business owner and Whangarei District councillor, was walking from Forum North to the central library when the masked men ran past him.
One was carrying a bag and the other was empty-handed, he said.
Benney chased them for about 100m along a footpath between Forum North and the central library and over a bridge leading to Second Ave.
"It was fairly obvious what was happening when they ran past me. One guy was lagging behind the other and appeared to be a bit unfit so I thought 'I'll catch him'," Benney said.
"Just as I was about to grab him, he yelled out to his mate who was ahead of him and who then passed him a sawn-off rifle. That rifle was then pointed at me.
"I put my hands up and said 'no worries, you go'. I could tell from my 30 years of policing that it was a real gun, not a plastic toy."
Benney, who left the police force in 2013, said after the robbers left him, he again gave chase along Second Ave but stopped after seeing them leave in a red Commodore.
Had has had firearms pointed at him twice before, when he was a police officer based in Hikurangi.
ANZ spokesman Stefan Herrick said a small amount of cash was stolen during yesterday's aggravated robbery.
He said the bank would offer counselling to staff and customers affected by the robbery.
The bank was closed for the rest of the day after the robbery and may not re-open today."It will largely depend on whether staff feel up to going back to work after what was an extremely frightening experience," Herrick said.
Detectives spoke to bank staff and members of the public on Rust Ave while a scene of crime Officer dusted for fingerprints inside the bank.
Workers at businesses along Rust Ave were not aware of the robbery until police cars turned up.
Whangarei Intermediate School went into lockdown from 11.55am until 12.45pm.
All students and staff were safe.
If you have any information that could help the police investigation, please call 111 immediately or contact Whangarei Police (09) 430 4500.
Police have advice for people who come across a crash scene.