Police are trying to trace the steps of an 18-year-old man hit by a milk tanker on a remote part of State Highway 1, near Oamaru early this morning.
The man was flown to Dunedin Hospital in a status 1 condition, suffering head and chest injuries, after he was hit by the truck a kilometre south of Maheno about 1.12am.
The incident occurred near the intersection of SH1 and Currie Rd, an ambulance spokesman said.
The man remains in a serious condition in intensive care. His next of kin in Maheno have been notified.
The truck which struck the man was travelling north, Senior Sergeant Craig Brown of Dunedin Police said.
Enquiries were underway to determine whether the man had come from a party or pub, and where he was on the road when he was struck.
Police blocked the road until 11am.
The driver of the milk tanker was shaken but unhurt, police said.