Debbie Ashley, 61, a resident of Gadsden, Georgia, was camping nearby when she was jarred awake by what she thought were gunshots.
But then she looked outside, spotted the fire and drove to the scene to take footage of the blaze.
"I opened the door, and I could see it glowing over the hills," she told NBC News. "I got my dog and drove down there."
Seven boaters were treated at a local hospital, most for hypothermia having jumped into the water to escape flames, officials said. It was about 43 degrees in Scottsboro when the fire began.
"Multiple boats sunk, some of them at the dock, some of them floated away from their moorings ... and sunk in the lake," Necklaus said.
WATCH: Sun is up and we’re getting a much better look at the devastation from the overnight fire at the Jackson County Marina. Investigators are still working to determine how many fatalities there are. @waff48pic.twitter.com/jq26MIJyw2