Police say a man was found on the Loughgall Road, Portadown around 11.30pm on Saturday with a “significant head injury”.
In a post on Facebook, PSNI Craigavon said: “How he came to be there, we don’t yet know, but it’s possible he was hit by a car which then drove on. We are unsure how long he had been lying there for.
“At one stage this male was left unconscious.
If you were on the Loughgall Road last night, saw a male who you had any concerns about or witnessed any collision, moreover if you hit something which you may now believe, reading this, could have been a person, it’s vital you contact us immediately.
“The incident number is 1608 of 04/08/18.”