Ten people die in Hunter Valley bus crash, 25 others taken to hospital

Ten people have died and multiple others have been injured in a bus crash in the NSW Hunter Valley overnight. 

Key points:The bus rolled on a roundabout in the town of Greta in the NSW Hunter regionTen people have died, and 25 have been hospitalisedMotorists have been advised to avoid the area

Emergency services were called to Wine Country Drive at Greta just after 11.30pm last night.

The party is believed to have been travelling to Singleton from a wedding at winery venue Wandin Estate.

"We're still waiting for further details to come to light as the investigations continue. We don't know the circumstances around the crash at the moment," Cessnock mayor Jay Suvaal said to ABC News Breakfast on Monday.

"But it does appear it was a wedding chartered bus that had been coming from a wedding earlier that day." 

Police say 10 people have died but the toll could rise.

The coach rolled on a roundabout near the Hunter Expressway after overturning, said police.

Police said 10 people have died but the toll could rise, with 25 others taken to John Hunter and Maitland hospitals and Royal Prince Alfred Hospital in Sydney. 

The other 18 passengers were uninjured.

Winery Wandin Estate is a popular venue for weddings.(Supplied)

The bus driver — a 58-year-old man — was taken to hospital under police guard for mandatory assessment. 

A crime scene has been established and an investigation into the cause of the crash is underway.

The large-scale emergency response team will involve police, traffic and highway patrol, paramedics, fire and rescue personnel and helicopters for hospital transports.

Driver arrested after mandatory testing

Acting Assistant Commissioner Tracy Chapman said officers responded to a single motor vehicle collision. 

"The driver of the coach was taken to hospital for mandatory testing, he is now at Cessnock police station and currently under arrest."

Assistant Commissioner Chapman said charges against the driver were pending. 

Acting assistant commissioner Tracy Chapman said charges are pending against the driver.(ABC News)

The bus remains on its side and is yet to be righted, and there is the potential that people are still under the vehicle, she says.

"From a policing perspective, our role is to make sure we undertake a full and thorough investigation to ensure that some comfort may be given to those family members and the public at the conclusion of the investigation and that process."

As far as police are aware, there were no children on board.

Victim identifications are still underway. 

'Sympathies and thoughts'

Prime Minister Anthony Albanese shared his "deepest sympathies" online on Monday morning. 

"For a day of joy to end in such devastating loss is cruel indeed," he wrote on Twitter.

"Our thoughts are also with those who have been injured."

Mr Suvaal explained the accident took place off the major highway near Greta and Branxton.

The region is a popular wedding and events destination.

"I'm unfortunately in the same situation as many people waking up to this horrific news," he said to ABC Radio National.

"It is a small community out there, but truly tragic events that I'm sure the community there will be waking up to the shock of it all today."

Mr Suvaal expressed gratitude to the first responders on the scene, including assistance from Cessnock, Singleton and Maitland.

"I would like to pass on my sympathies and thoughts to the families and friends of those people involved."

He said the local council will be offering support to emergency services and police throughout the day. 

NSW Member for Cessnock Clayton Barr added it was all hands on deck in the immediate aftermath of the crash. 

He told ABC NewsRadio it was a full-sized charter bus that would not be on the same bus route as regular public transport.

"Probably everyone on the bus was known to each other," he said. 

"There's a very high chance that the 18 people who haven't needed [to go] to hospital are going to be shattered today because their friends … are in those numbers."

Emergency services took injured passengers to hospitals across the Hunter Valley and Sydney.(ABC News: Keely Johnson)

Minister for Regional Roads and Maitland MP Jenny Aitchison described the crash as a "terrible tragedy".

"Everybody is pulling together and basically it will be a case of making sure that the families and the community are supported in such a terrible time," she said.

Wine Country Drive closed

Wine Country Drive is closed in both directions in Branxton, between the New England Highway and Bridge Street.

Motorists have been advised to avoid the area and use an alternative route.

Live Traffic NSW says there is no access to Wine Country Drive from the Hunter Expressway.

The road closures are expected to be in place for some time.