"Everyone just fell. There was only one way for them to go."
His partner said there was no warning before the deck came away from the side of the house, but a huge bang as it collapsed.
"Luckily we had a few friends here who were paramedics, firemen and police - so they were able to take charge and keep people pretty calm," she said.
The couple had a building inspection done before buying the house.
"So we didn't feel like we should have to check our own home. It's pretty obvious looking at it today though that it [the deck] has been built pretty horribly ... pretty shoddily. I don't know how it's been signed off really," the builder said.
He said it appeared the deck had simply been nailed into the side of the house, rather than fixed to a supporting structure to reinforce it and make it stable. "I don't even know how it's been connected at all. It's just floating there."
An Auckland Council spokeswoman said it was likely the matter would be looked into this week - including searching through building consents and applications relating to the deck.