A head-on collision north of Masterton on Friday, September 11. Two people were critically injured. PHOTO/STAFF REPORTER

Two people were flown to Wellington Hospital on Friday afternoon after a head-on crash north of Masterton.

At the time of publication, both remained in a critical condition.

The crash, which happened at about 1.35pm on Friday at Kiriwhakapapa, forced the closure of State Highway 2 while emergency services were at the scene.

A Wellington Free Ambulance spokesperson said two ambulances and two helicopters responded to the crash, as well as a WFA shift manager.

The conditions of the road on Friday were wet, slippery, and sleet-lined after a weather-bomb struck in the early afternoon.

The Serious Crash Unit was investigating the crash, and the road reopened at 5.25pm.

At the same time as this serious crash, another vehicle lost traction and crashed through a fence and into a paddock on Paierau Rd, Masterton, but there were no injuries.