Police are calling for sightings of a late-model white 4x4 ute that was heading out of Wanaka, on the north side of the Maungawera Hill towards Hawea, sometime between 6.15am and 6.45am today.
The ute may have been in the area at the time of the incident and police would like to talk with the driver.
Rosie Foster, who was house-sitting at a friend's Bed and Breakfast right by the crash scene, said she did not hear the crash, but heard sirens early this morning.
She had spoken to a police officer who told her the passenger of the fatally injured driver had to grab the steering wheel.
"He said that something had flown out the back of a car and hit the windscreen of another car, and gone straight though and killed the driver.
"The passenger managed to grab hold of the steering wheel and steer it. I'm not sure if they had a massive crash after that."
Ms Foster said police did not know what the object was and had not found it despite searching the grass along the sides of the road.
"They said it could be anything from something that's flown off the back of a trailer or even if they've thrown something out the window."
Ms Foster said police were also investigating marks on the road where it looked as though a vehicle had turned around and gone back up the road.
However, she said police were unsure if the marks were caused by the vehicle the object came from, or whether they were caused by emergency vehicles on the scene.
Detective Sergeant Brian Cameron said police had searched for the object extensively today but it had not been found.
"It's still a bit of a mystery as to what the object was and we will be searching the scene again tomorrow," he said.
Police would also be stopping cars along the same stretch of road between 6am to 7am tomorrow.
They would ask drivers whether they had been on the road at a similar time today, and whether they saw either the blue Subaru or white ute.
"We still very much want the help of members of the public to help us piece together what exactly has occurred," Mr Cameron said.
Police said no further details about the man who died in the crash would be released until next of kin have been notified.
Anyone with information could contact the Wanaka police station on 03 443 7272 or their nearest police station.
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