Two foreign nationals were killed this afternoon in a collision near Pelorus Bridge in Marlborough.
One of the deceased was the driver of a vehicle and the other was a rear passenger. Both are males.
A female front seat passenger and the local female driver of a ute involved in the crash have both been taken to Wairau Hospital with serious injuries.
Senior Sergeant Peter Payne of Marlborough Police said it appeared one of the vehicles had crossed the centre line.
He said conditions at the time were atrocious, with torrential rain and low cloud.
Police are now working to formally identify the deceased.
State Highway 6 between Nelson and Blenheim now has one lane open.
Drivers are urged to take extreme caution and drive to the conditions.