A gas tanker has rolled and caught fire after colliding with a truck on State Highway 1 in Greta Valley, North Canterbury.
A St John spokesman confirmed one person had sustained serious injuries and would be flown to hospital by a helicopter.
A freight truck collided with the gas truck near a intersection with Scargill Valley Rd and Valley Rd about 9.10am.
The gas truck has come to a stop on a grassy verge alongside the state highway and gas canisters have fallen around it.
The area of SH1 near Omihi Rd is closed to all vehicles.
Police have advised the road may be closed for some time and the Serious Crash Unit is attending the scene.
Greta Valley is about 83 km north of Christchurch