Siu Manu, a Samoan seasonal worker and a father has been identified as one of the two passengers killed in a minibus crash that injured nine others.

Mr Manu was killed after the bus rolled and struck a tree along the Calder Highway in Carwarp, near Mildura, in Victoria's north-west, at 7.45am on Tuesday.

According to the Daily Mail, two people, including the male driver, suffered critical injuries and were flown to The Alfred Hospital and Mildura Base Public Hospital.

Media report say three passengers suffered serious injuries while the remaining four sustained minor injuries with the group taken to Mildura Base Public Hospital.

Most of the passengers are understood to be farm workers from overseas.

Loved ones took to social media to mourn the death of Mr Manu who was from Samoa and employed as a farm worker in Australia.  

'We are blessed because of you brother. Rest in peace,' one wrote.

'I hope father in heaven will comfort you and the children,' another added.

'What a hardest pill [sic] to swallow, but sometimes we have to accept the fact that God need them the most,' a third wrote.

His brother Tuuinaifo, who lives in Samoa, told the Herald Sun his older sibling was a kind man who always helped his family.

'He's the one who supported and helped my mother throughout, often paying our school bills,' he said.

Ambulance Victoria dispatched several crews including an air ambulance helicopter, advanced life support and mobile intensive care paramedics to the scene say media reports.

Shocking footage showed several workers climbing out of the wreckage of the bus.

One man was seen lying on the ground unconscious and a female worker was heard saying 'talk to him, keep him warm'.

A Victoria Police spokeswoman told Daily Mail Australia investigations remain ongoing and the cause of the crash is not yet known.

Senior Highway Patrol officer Mark McDonald said on Tuesday police believe the minibus was trying to overtake a car before it crashed.

'It was quite a serious accident. It's difficult to see why it happened,' he said.

Victoria Police are still investigating the incident, which left two people critically injured and several others with serious injuries (pictured crash scene)

The driver of the car, along with other motorists who witnessed the crash, are assisting police with their inquiries.

Police are still trying to identify the passengers and attempts are being made to contact their families.

A section of the highway between between Kulkyn Way and Brownport Road remains closed.