The B-double truck was travelling in front of the bus when its trailers dislodged, blocking the highway and causing the crash near Pimpinio, west of Horsham, about 2am on Thursday.

The 36-year-old male truck driver from Murray Bridge was released pending further enquiries, police said.

His 22-year-old passenger, a woman from Murray Bridge, has been charged with drug trafficking, possession and use and is due to front Ararat Magistrates court on Friday.

Bus driver Emil Pich, 60, died at the scene.

The Melbourne grandfather has been hailed as an "amazing person" after his selfless evasive action at the last minute meant he "took the brunt" of the accident.

A spokesman from Mr Pich's bus company, Firefly, said he had worked for the business for over 25 years.

"Obviously everybody's devastated. He's survived by his mother, brother, sister, three children, and seven grandkids.

"It's having an impact on everyone here, losing a team member and friend."

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