A 34-year-old man remains in a critical condition in the Royal Victoria Hospital after being stuck by a car in Moira.
The collision happened around 2.40am on Saturday.
The pedestrian had been walking close to a railway halt on the Glenavy Road when the collision happened.
The road remained closed for most of Saturday morning while police examined the scene.
Inspector Paul McCarron has asked that anyone who witnessed the collision, or who was in the area at the time and who can assist the investigation, call 101 and speak to police.
SDLP councillor for the area, Patrick Catney, said the “injuries this man has received are very sad especially at this time of the year”.
“An accident at any time of the year is awful, but to happen now days before Christmas when families are flying in from around the world to be together makes it much worse,” he said.
“My thoughts are with the family of that young man. The community now has to pray and hope for the best for this man.
“No one wants something like this visited on their doorstep. No one wants that knock on your door. We also have to commend our police and ambulance services for dealing with accidents like this.”
UUP Alderman Jim Dillon said the incident in the early hours of Saturday “was another tragedy to happen on our roads”. “It is a terrible thing to happen to any family a few days before Christmas,” he said. He appealed for motorists to be vigilant.