NZTA says a fatal two-vehicle car crash in the Manawatu-Whanganui region's Mangaweka, will cause major travel headaches

Emergency services were called to State Highway 1 around 12:40 this afternoon, with the road closed to north and southbound traffic.

It's unclear how many people have died in the crash.

NZTA says the highway could remain closed between Waiouru and Marton for several hours into the evening, and involve delays of two hours or more.

An alternative route on State Highway 4 via Whanganui, is expected to add more than two hours to travel time.