Emergency services freed a man trapped inside a truck carrying dangerous goods that crashed in central Waikato on Tuesday morning.
The Fire Service said two oncoming trucks collided on State Highway 27 between Matamata and Tirau just after 6am.
It said one of the trucks was carrying bulk gases including oxygen, acetylene, and propane cylinders.
The seriously injured driver was eventually freed from the truck and flown by helicopter to hospital. The other driver was unharmed.
Waikato police said the gas cylinders were made safe, and the highway was reopened on Tuesday afternoon.