Dry weather and variable winds have fueled the blaze, which consumed 1,000 acres overnight, The Virginian-Pilot reported. More than 150 firefighters, many of them from out of state, were in the swamp, C.J. Norvell, a spokeswoman for the Southern Area Incident Management Blue Team, said.
The fire was reported a week ago but is believed to have started from a lightning strike several days earlier. It spread into the North Carolina portion of the refuge this week.
Barb Stewart, a spokeswoman for the firefighting team, said dead trees downed in 2003 by Hurricane Isabel have provided fuel for the flames.
"That stuff out there, it's dry, there's a lot of it, and it wants to burn," she said.
The Baltimore Sun reported Tuesday smoke from the fire could be smelled in Annapolis, Md., and Washington, blown north by the wind. On Wednesday, smoke from the fire was visible in pictures taken by satellites.