Well-wishers shared images of the idyllic setting at the Wandin Valley Estate for the ceremony and celebrations afterwards.
But just hours later the bus carrying wedding guests rolled over in foggy conditions killing 10 people and injuring 25, NSW police said.
The 58-year-old driver was arrested and being held at a Cessnock police station and will be charged, Police Assistant Commissioner Tracy Chapman said.
She would not detail the allegations, including whether speed was a factor, but told reporters “there is sufficient information … for us to establish that there will be charges.”
The crash happened just after 11.30pm on Sunday in foggy conditions at a roundabout on Wine Country Drive in the town of Greta in the Hunter Valley region of New South Wales state north of Sydney.
The guests were heading for their accommodation in the town of Singleton, Chapman said. One guest told Seven News it had been a nice day and a fairytale wedding.
A motorist who drove past the crash scene, identified by Australian Broadcasting Corp, only as Alison, said the fog was so heavy she could not make out the colours of the flashing lights of police cars, ambulances and fire trucks.
She told ABC: “The fog was terrible, it was super foggy. You could barely see in front of you.”
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Of the 25 people injured, 21 remained in hospitals late Monday morning and one was in critical condition, the state government said. The conditions of the others were described as stable.
Police had said 18 passengers escaped injury. But police later said there were only 36 people on the bus: the 10 dead, the 25 injured and the driver. The 18 were the least seriously injured among the passengers taken to hospital.
Police Commissioner Karen Webb said investigators had not yet determined what caused the bus to roll on its side. She said: “The cause may not be known for some time. It will require scientific examination.”
Whether the vehicle had seat belts and whether passengers were wearing them also “will come under scrutiny,” she added. Prime Minister Anthony Albanese thanked first responders and offered government support to victims and their families, saying the “mental scars of this will not go away.”
He said: “For a joyous day like that, in a beautiful place, to end with such terrible loss of life and injury is so cruel and so sad and so unfair. People hire a bus for weddings in order to keep their guests safe. And that just adds to the unimaginable nature of this tragedy.”
Jay Suvaal, the mayor of Cessnock, said the crash was “truly horrific.”
He said: “We are a major wedding and tourist destination in the Hunter Valley, and so there will be people from all over the state and the country that have been to these areas and have probably done similar things, I think it will send shock waves right through the broader community.”
Greta is in the heart of the Hunter Valley wine region, a picturesque area dotted with vineyards and restaurants. It was the first wine region established in Australia.
The wedding was in the middle of a long weekend, with Monday a public holiday across most Australian states.