A bus driver was driving too fast when the vehicle rolled on its side and hit a guard rail in heavy fog in an Australian wine region, killing 10 wedding guests and injuring 25 others, police alleged on Tuesday.

Brett Andrew Button, 58, was driving 35 passengers on a 20-minute journey from a wedding reception at the Wandin Estate Winery to the town of Singleton, both in the Hunter Valley wine region of New South Wales, when the 2009 Volvo bus rolled at a roundabout late on Sunday.

Button allegedly said “fasten your seatbelt” to his passengers before the fatal crash, news.com.au reports.

Button had been in police custody but was released on bail when he appeared in the Cessnock Local Court today charged with 10 counts of dangerous driving in relation to each death and one count of negligent driving.

Earlier, acting Police Assistant Commissioner David Waddell alleged that Button “entered that roundabout driving in a manner that was inconsistent with the conditions.

“Obviously, the speed was too quick for him to negotiate that roundabout, causing the vehicle to fall on to its left side and cause those injuries,” Waddell told reporters.

It was Australia’s most deadly road accident since 1994, when a bus skidded on its side across a highway and down a steep embankment in Brisbane, killing 12 people and injuring 38.

Assistant Commissioner Tracey Chapman addressed the media near the scene of a bus crash in the Hunter Valley. Photo / AP

Police said Button underwent mandatory blood and urine testing for drugs and alcohol Sunday night but no impairment was detected.

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Prosecutors had argued against Button being released on bail. But Magistrate Robyn Richardson said his family ties and bail conditions could reduce his risk of fleeing the country or interfering with witnesses. She also noted a trial was unlikely to be heard before late 2024.

His bail conditions include that he does not drive and that he observes an overnight curfew at his Hunter Valley home of Maitland.

Button sat with his head bowed throughout the short bail hearing and wept when Richardson noted that he was clearly suffering along with the rest of the community that had been devastated by the crash. She said there were concerns about his wellbeing.

A couple place flowers at a roadblock in Huntlee near the scene of a bus crash in the Hunter Valley. Photo / AP

Police statements made by 10 passengers about Button’s “prolonged behaviour” before the crash created a strong prosecution case, she said, without elaborating on that behaviour.

Prosecutors said Button could face further charges in relation to the seriously injured survivors.

Of the 25 passengers taken to hospitals, 14 had not been discharged, with two remaining in an intensive care unit in critical but stable condition, Waddell said.

The dead and injured were aged from their 20s to their 60s, Waddell said.

He declined to comment on media reports that Button told passengers through the bus’s microphone shortly before the crash, “If you think that was fast ... watch this.”

Waddell also declined to comment on reports that passengers were standing moments before the crash.

Linq Buslines, which provides school bus and event charters, owns the bus involved in the crash. Its website says all its buses are equipped with seat belts.

New South Wales law requires bus passengers to use seat belts if they are available.

- Additional reporting by Herald staff.