Detective Chief Inspector William McKenna, of Richmond Police District, described the scene where two men were killed as "horrific" for witnesses and emergency service workers.

He said the truck driver was "obviously ... in shock" and taken to hospital after the incident where mandatory blood and urine testing took place.

"You won't have those results yet for a number of weeks, but he will then be assisting police with our inquiries," Detective Chief Inspector McKenna said.

"He's seen the stationary vehicles but unfortunately he hasn't seen the two males fighting on the northbound lane,"

"He's collided with both of those persons causing fatal injuries."

The officer said blood samples from the two deceased drivers would also be part of the post mortem.

EARLIER: A B-double truck driven by an Albury man struck and killed two men on the Pacific Highway south of Ballina on Monday evening.

NSW police are trying to formally identify the deceased men, who were the drivers of an SUV and a semi-trailer carrying logs both travelling south about 8pm.

Police were told the drivers were involved in a minor altercation, stopped about five kilometres south of Woodburn and got out of their vehicles.

"Witnesses have told officers from Richmond Police District the men were fighting in the northbound lane when they were struck by a B-double being driven by a 35-year-old man from Albury," a police statement said.

Both men sustained multiple injuries and died at the scene

"It's believed the SUV driver is a Grafton man aged in his 30s, while the driver of the semi-trailer is from Smiths Lake, aged in his 40s," the statement said.

"The driver of the truck was taken to Ballina Hospital where he has undergone mandatory blood and urine testing."

The highway was closed for almost nine hours while the crime scene was examined.

Richmond officers are continuing inquiries and have called for witnesses to the incident to contact them via Crime Stoppers on 1800 333 000.

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