Residents of the South Island city have described hearing the sound of an explosion “which sounded like a bomb going off”. Police say that initial reports came from a number of people who had been injured in the explosion in the residential suburb of Northwood. The police said in a statement that a house was on fire and the road had been closed off.
Evacuations were being carried out while police remained on the scene.
It comes just four months after the city was devastated in the horrific terror attacks in which 51 people were shot dead.
The deceased and injured were wounded at two attacks on mosques in the city.
The atrocity was described as the worst peacetime mass shooting in New Zealand’s history.
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According to the New Zealand Herald newspaper, an unnamed Christchurch hotel worker said a sound like an explosion was heard and nearby buildings were left shaking.
They said: “It was more than an earthquake, you’d think a bomb had gone off.”
New Zealand emergency services said the suspected Christchurch blast was a gas explosion and there was no indication of any wider security implications.
Local reports say that six people have been injured and are en route to hospital.
Injuries are said to range from moderate to critical following the gas explosion.
Emergency services have blocked off the site.
Tom White, who works at the nearby Styx Mill Country Club, said he saw concrete tiles be blown at least 100m in every direction.
He added: “The house is matchsticks. It’s totally blown apart.”
“It’s caused a lot of destruction to other houses, its blown the garage door right of the next-door neighbour’s house.”