A 71-year-old man was killed when his car collided with another vehicle on State Highway 1 southeast of Blenheim today.

Police said it appeared the Subaru station wagon which the man was driving drifted across the centre line near Ward at about 1.50pm before colliding with a 4WD vehicle which was towing a trailer.

The man in the Subaru died as rescuers tried to get him out of his upturned car.

Sergeant Jason Munro from the Blenheim police said a third vehicle which had been following the southbound 4WD crashed off the road while trying to avoid the collision.

Four occupants of the two southbound vehicles were taken to hospital in Blenheim - three were discharged this evening while the fourth was expected to remain overnight.

A child in the third vehicle was uninjured.

The southbound motorists were all believed to be related and were returning to Christchurch after a holiday in the Nelson region, Wellington-based Westpac Rescue Helicopter spokesman Dave Greenburg said.

The crash caused delays but the road was cleared and reopened, with traffic flowing normally, before 5.30pm.

It was only the second road death of the holiday period, after Ngaruawahia man Paul McLaughlin was killed in a crash in Waikato early on Christmas Day.

Mr McLaughlin was thrown from his car after it clipped a guardrail, crossed the centre line and crashed eight metres down a steep bank on State Highway 1, at Hopuhopu, 3km southwest of Taupiri, about 1.20am.

The official holiday road toll period began at 4pm on December 24 and runs until 6am on January 5.

Holiday road toll (4pm December 24th - 6am January 5th)