Arriving guests were told the wedding was off after the crash.
All four people on board the helicopter were injured - three seriously and one moderately - after it crashed at Terrace Downs Resort in Windwhistle, 80 kilometres west of Christchurch, about 3pm.
Photos from the scene show the Robinson 44 helicopter right side up but with its tail sheared off, near a golf course sand trap.
Terrace Downs Resort press officer Louise Paul said a bride and groom planning to marry at the resort today were on the helicopter when it crashed, along with the pilot and one other person.
She didn't know who among those on board were the three seriously injured - all of whom a St John Ambulance spokeswoman said were flown by rescue helicopter to Christchurch Hospital. The less injured victim was taken by ambulance to the same hospital.
"It's very upsetting for them," said Paul.
Other guests, unaware of the crash, were still arriving for the nuptials.
"The wedding guests are just arriving now and we're letting them know."
The helicopter company thought to be involved is Christchurch-based.
Paul didn't see the crash or know what had gone wrong.
The manager of the resort was among those who went to help after the alarm was raised.
According to its website, Terrace Downs Resort, next to the Rakaia River is a "premier destination for weddings, corporate events and luxury getaways".
"In the shadow of the majestic Southern Alps, Terrace Downs Resort lies in the heart of the picturesque Canterbury region.
"An ideal 'getting away from it all' destination close to Mt Hutt ski field and Methven, it is a premier destination."
Bride and groom can arrive by horseback, golf cart or helicopter, according to the website.
The crash was reported to police at 3.05pm, a police spokeswoman said.
Two crews each from the Hororata and Methven volunteer fire brigades attended, Southern Fire and Emergency shift manager Simon Lyford said.
