A man was killed when a truck apparently crossed over into oncoming traffic on the Hume Highway early Saturday, police say.

NSW Police said emergency services were called to the crash on the south bound lanes of The Hume Highway near the Medway Road off ramp near Berrima about 4am.

"Police believe that a north bound B-double truck crossed to the south bound lanes of the highway and collided with several vehicles," they said in a statement.

"The male passenger in one of those vehicles, a utility, was trapped and could not be revived."

Police are investigating the circumstances of the crash, and ask anyone who saw it, or the events leading up to it, to contact them.

The southbound lanes of the Hume Highway were closed on Saturday, with traffic being diverted onto Medway Road.

It's the third serious truck crash in that area in a week.

Emergency services were called to the Wingecarribee River Bridge, where they found a prime mover and trailer, carrying frozen goods, well alight shortly after 9am on Wednesday.

The driver, aged in his 60s, was the only person in the truck. He was treated at the scene by NSW Ambulance paramedics for minor injuries and taken to Bowral District Hospital.

A truck carrying fibre glass and pool materials caught fire on Monday.