Two people have been airlifted to Christchurch hospital after a two-car crash north of Kaikōura this morning.

A St John spokesperson said one person is in a critical condition and the other is in a serious condition.

Emergency services were called to State Highway 1 near Wilderness Rd just before 4.30am.

Fire and Emergency shift manager Lyn Crosson said two vehicles were involved.

"Two people have been extricated but emergency services are still on the scene."

A police spokesperson said emergency services were attending a serious two-vehicle crash on SH1, near Wilderness Rd, Kaikōura where "two people are understood to have been seriously injured".

"The road is expected to remain closed for some time, with diversions in place, while the Serious Crash Unit examines the scene.

"Motorists should avoid the area, if possible."