A good samaritan who stopped to assist a two-vehicle collision was robbed of their vehicle when a person involved in the crash fled the scene.
Police were called to the collision on Poihipi Road near Taupō, Waikato, at 7am on Thursday.
Two people have been hospitalised in a serious and critical condition.
A post on a community Facebook group claimed the alleged offender stole a green Holden ute from a person who offered their help.
The author of the post said the "serious" accident had been a head-on collision.
"My partner witnessed the accident, the guy who stole the ute was going more than 100km, crossed the centre line and ended up on the other side of the road," one person alleged.
Police are searching for the suspected offender and cordons remain in place.