An argument, not road rage as initially suspected, led to a fatal shootout Sunday evening in DeKalb County, police said.

Two men pulled into the driveway of a home in the 3400 block of Rainbow Drive around 7 p.m. They knew one another and got into an argument that escalated to violence, police said.

"There was some gunfire exchanged," DeKalb police Lt. Dane Cunningham told Channel 2 Action News. "One of the subjects was shot in the head."

That individual died en route to the hospital, police spokeswoman Mekka Parish said.

The other man drove himself to the QuickTrip gas station at Rainbow Drive and Wesley Chapel Road, where he passed out.

He was taken to Grady Memorial Hospital, where he was in critical condition Monday, Parish said.

Neither man is being identified at this time. It is unclear why the men were arguing.

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-- Staff writer Mike Morris contributed to this article.