The evacuation of thousands of concert-goers from the Homegrown Music Festival last night was reportedly sparked by a tattoo.

Police said on Sunday morning that initial concerns were "to do with a tattoo" however they said the concern "was a mistake".

It has been reported the tattoo was thought to be linked to far-right ideology, however, it turned out it was traditional.

Around 5000 concertgoers were evacuated from the main stage at the Homegrown Festival in Wellington around 9.20pm.

Homegrown spokeswoman Kelly Wright said the incident was "an innocent misunderstanding".

"Some of the Homegrown crew identified a person that they were concerned about and police made the call that person needed to be found," she said.

"It all happened at the change-over of the music so people were moving around and police couldn't spot the person immediately so they made the call to evacuate the stage.

"The person was found and it turned out that is was a completely innocent misunderstanding and everyone was allowed to return."

Wright said it was unfortunate that it happened but all other four stages carried on as normal.

The incident happened just before a minute silence was planned in tribute to the Christchurch mosque shooting victims.

"It happened at 9.21pm and the minute silence was going to be 9.25pm," she said.

Wright said while the main stage was affected, the rest of the crowd had an "incredible, heartfelt moment".

She said the whole evacuation took 28 minutes before main act Shapeshifter returned to the stage.

"They did an amazing set and only missed about 10 minutes.

"It all turned out good but it was unfortunate that it happened and people were inconvenienced," she said.

When asked whether the incident stemmed from a tattoo, Wright said that information was incorrect.

Last night police clarified the decision to evacuate was made by police rather than Homegrown staff.

"A person has been spoken to and the area searched, and as a result Police can confirm there has been no threat to the Homegrown festival or the public," they said.

"While the concern in this case appears to have been an innocent misunderstanding, Police would like to remind people to stay vigilant and call 111 if they see anything suspicious."

The event took place on Wellington's Waterfront, beside Te Papa. Around 20,000 people were expected to attend the show.

Other major events, including Pasifika in Auckland, were cancelled after the Christchurch terror attack. But the organisers of Homegrown decided to go ahead with the show.

After the Christchurch terror attack, police appealed for the public to be vigilant and report anything suspicious.

Experts warned the country would be on edge for some time.

Significant events like the Christchurch mosque shooting triggered a range of psychological effects including "hyper vigilance".

It is a condition which has our senses enter an enhanced state of sensitivity. People become more highly attuned to their surroundings, find they constantly scan the environment and absorb and process information for anything which signals danger.

Dr Ian de Terte, a senior lecturer in clinical psychology at Massey University's School of Psychology said people can also feel compelled to be more attuned because they feel it is their responsibility to do so.

"There is that heightened awareness of what's happening. The connection between cues."

De Terte said the motivation could be "fight or flight" but he also believes it is driven by a desire to help - to somehow make a contribution.

It's not a rational choice to respond in this way. It's instinct.

"People don't make rational choices. They go back to what they think is going to make them survive."

For most, the state of hyper vigilance will recede in months.