There was panic on Sunday night for Bay of Plenty residents when a series of sirens sounded around 9.30pm.
Many of the public assumed a tsunami was on its way, and rushed to higher ground.
"I'd like to thank all those people who last night evacuated at the sound of the sirens," Fire and Emergency national commander Kerry Gregory said.
But the sirens were a false alarm and nothing to do with Civil Defence's tsunami warning system.
"The areas that reportedly had activations, which ranged from Te Puke, up through Tauranga to Waihi – there are no Civil Defence tsunami sirens in those locations at present. So those wouldn't have been activated under our protocols," Bay of Plenty emergency management director Clinton Naude said.
The sirens that went off are mostly used by Fire and Emergency services to call volunteer firefighters. Fire and Emergency spent all day today getting to the bottom of how they were triggered.
"This is the result of one of our legacy systems," Gregory said. "We're trying to get down into the details, technically, what happened to allow those to activate.
"We've put in place some patches. It's not a long-term fix for us but it's patches to ensure that it's not going to happen again tonight.
"We don't want to put a patch and a fix over this one area and then another area goes tonight somewhere else.
"So what we've been doing today is tracking down exactly where these legacy systems lie, across the country, and make sure it's safe in all those areas as well."
The false alarm has highlighted a lack of knowledge about tsunami warning systems.
"If there's a tsunami threat to New Zealand, including the Bay of Plenty, the alerting systems we use are the emergency mobile alert which is broadcast to mobile phones," Naude said. It's a system we used when we tested it late last year as a national test.
"This is supported by the Red Cross Hazard app, which is a free app to download and set up your alerts. We also use our supporting networks which include the radio and television broadcasters, social media and other platforms."
Yesterday's sirens were the second false alarm in 12 months leaving the public uncertain about how to know when to evacuate.
Adding to the confusion, Naude says sirens could still be used in the event of a large tsunami emergency.
"There's always options to use them but no arrangements exist at present, and some of that could be the confusion that arises from the different tones, or the tones that people hear for those sirens."