Alex Woolcock was driving the Hyundai i30 involved in the crash at midday on Monday, and said he guessed it "wasn't our time to go".

"It's not everyday you're able to walk away from that just feeling stiff," Mr Woolcock told the NVI.

According to Gunnedah police Senior Constable Kate Gough, a second car "turned across the path" of Mr Woolcock and his passenger on the highway near Blue Vale Road.

She said the i30 then crashed into the oncoming car which forced it into the side of the semi-trailer.

"One vehicle collided with another vehicle, and as a result of that, it veered into the side of the truck," Senior Constable Gough said.

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Mr Woolcock said if the incident had occurred a second later, he and his passenger would've been "t-boned" by the oncoming "cruiser".

"It would [have] been a different story for the driver of the cruiser and us. And if we were speeding it would be been a totally different story for the truckie so I'm glad everyone's okay," he said on Tuesday.

"It was awesome job by the first responders, ambos and firefighters."

Mr Woolcock and his passenger, a man in his mid-50s, were taken to hospital after the incident.

The truck driver was also taken to Gunnedah hospital for mandatory testing.

The SES and Fire and Rescue Gunnedah were also deployed to the crash after the semi-trailer spilt 50L of diesel it was carrying in a 600L tank onto the highway.

Firefighters contained the leak and the truck was moved off the highway.

Senior Constable Gough said further investigations were ongoing "as to what's actually occurred".

No charges have been laid.