RALEIGH, N.C. (AP) — A wildfire in Pender County has grown to slightly more than 30,000 acres and continues to threaten surrounding residential and commercial buildings valued at more than $64 million, the county's emergency management director said.

Winds that had been blowing from the southwest shifted to the north Wednesday, elevating concerns about fire and smoky conditions on the south side of the Holly Shelter Game Land, director Tom Collins said.

"We are seeing a possibility for a super-fog event," Collins said.

Super fog occurs when water vapor mixes with smoke to create low- to zero-visibility conditions, according to a National Safety Commission website. Holly Ridge and Jacksonville may experience the heaviest smoke, Collins said.

About 2,100 homes stand around the perimeter of the game land, with most concentrated on the south end near U.S. Highway 17, Collins said.

The fire has covered about 50 square miles in less than two weeks and is now slightly more than 30 percent contained. A back-burn conducted Tuesday by the N.C. Division of Forest Resources helped eliminate fuel along the perimeter of the blaze.

Firefighters also are using heavy equipment to dig trenches and clear land along the edges of the fire to prevent sparks carried by the wind from igniting nearby grasses, brush and other materials, said state Forestry Services spokesman Brian Haines.

"Progress is being made, but our problem here is that there are no really good water sources," Haines added.

The ongoing drought dried most of the streams and creeks in the game land, Collins said.

Haines said firefighters are focusing on the northern edge of the fire as the wind begins to blow toward the south.

Northeast along the coast, in Dare County, the Pains Bay fire has burned slightly more than 45,000 acres since May 5. That blaze is no longer growing, and forestry officials said they are now focused primarily on eliminating hot spots at the center of the burned area.

West of Pender County, a fire near Bladen County's White Oak community has scorched nearly 1,400 acres, according to Chris Meggs of the Division of Forest Resources. The blaze started June 20 with a lightning strike and is about 60 percent contained. It lies within an area known as a Carolina Bay. The bays are large depressions in the earth thought to have been created thousands of years ago by impacts from meteors, Meggs said.

"It's hard to get equipment through the Carolina Bays," he added. "They are filled with organic soil on top of water, and they have a sand rim."

Firefighters have been back-burning along the edges of the White Oak fire. A public meeting was scheduled Wednesday evening to discuss additional fire containment plans with area residents.

A fourth blaze, in Sampson County, has reached 700 acres and is not currently threatening any homes or other development, a forestry division spokesman said.