Two injured after tornado strikes Christchurch causing roof to collapse

A violent storm has torn up the east coast of the South Island causing damage and injuries.

Two people sustained moderate injuries after a mini tornado caused a roof to cave in at the Savemart in the Christchurch suburb of Sydenham, St John says.

Two were injured when a tornado caused a roof to cave in.
Two were injured when a tornado caused a roof to cave in. Photo credit: Newshub/Alex Parsons, YouTube/Nic Muc

There were reports the mini tornado also shattered windows in the city.

Fire and Emergency New Zealand (FENZ) spokesman Anrdew Norris told Newshub multiple buildings were hit by the tornado in Sydenham.

"We had roofs come off buildings, air conditioning units pulled off the sides of buildings, powerlines down [and] trees over powerlines."

Lightning strikes started about seven fires in shelter belts, grass, trees and dunes.

Jamie Paull was in his workshop in the suburb of Waltham when the sky clouded over.

Two injured after tornado strikes Christchurch causing roof to collapse
Photo credit: Supplied/Jericho Forest

"It [the tornado] just had roofing iron in it, trees [and] there was a sheet of glass that got smashed," he told Newshub.

Paull said the tornado was "picking up everything in its path".

The hail that hit Christchurch.
The hail that hit Christchurch. Photo credit: Newshub.

"It was pretty impressive, and then the hail happened," he said.

FENZ assistant area commander Mike Bowden said the damage is widespread.

"There's been a swathe of damage through Christchurch," he said. "We understand there are properties that have lost roofing and there's been some other damage around the city."

A business in Christchurch's Wordsworth St was also cordoned off after roofing flew of the building. Analytix asbestos testing lab manager Gemma Newsome said contamination had spread from the roof.

"The risk to human health is relatively low but obviously there's going to be a massive clean up trying to remediate the area."

The tornado hitting over Christchurch.
The tornado hitting over Christchurch. Photo credit: Supplied/Stephen Keegan

Newshub cameraman Jabulani Ndebele said the area was a mess.

"Amazingly it [the storm] picked up an air con [sic] unit - and threw it right off the roof."

Further south, one person was critically injured and two people sustained moderate injuries following two crashes when the bad weather rolled through at Selwyn Bridge south of Burnham.

Earlier, emergency services were called to a house in the town of Palmerston, north of Dunedin, where it's understood lightning blew fuses and plugs off a wall.