A trick of the light on some sea fog created havoc on a New Zealand beach Friday when people saw what they thought was a tsunami rushing towards them.

A man who alerted beachgoers was called a “hoaxer” and taken in for questioning over the incident at Kairaki beach, north of Christchurch, but police later said he was not the only one fooled.

Police decided the man's concerns were genuine and the apparent sighting was confirmed by fishermen in the area, Senior Sergeant Tony Ellis said.

"With the weather as it is at the moment, combined with sea fog and refraction of light at long distances, this impression was gained by many people," he said.

The man convinced people that a tsunami was coming, creating havoc as people tried to leave the area.

There were no tsunami warnings in place.

"We hope that no one was hurt or unduly shaken during the evacuation of the areas," Sen-Sgt Ellis told the New Zealand Press Association.

Advance warnings of tsunamis were received at communication centers in time to advise the public, he said.

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