In another rural accident, a tanker taking milk to the Open Country factory in Wanganui rolled off SH4 and into a ditch near Aberfeldy around 10pm on Monday.
The driver was uninjured. Two Wanganui fire appliances, police and ambulance attended.
Horizons Regional Council was also called, and when its duty emergency manager arrived at midnight, bunds had been placed to stop a small leak of milk and diesel flowing into the Mangawhero River, Horizons' Adam Duker said. The tanker was carrying 600 litres of diesel and 27,000 litres of milk.
"It's extremely important milk doesn't get into waterways, as it has a high biochemical oxygen demand. When it gets into the environment, especially water, it strips away the oxygen and fish can't breathe," Mr Duker said.
Whanganui Fire Service's Jemal Weston said the tanker was likely to be put back on the road by a crane. Open Country staff members were unwilling to comment.