LAMAROO, Australia (CNN) -- Hundreds of firefighters are attempting to contain a massive bushfire that has been burning out of control since Thursday along the Victoria-South Australia border.

The blaze, believed to have been started by lightning, has already destroyed more than 250,000 acres of bushland. Airplanes are being used to drop water and chemicals onto the fire, while firefighters below are using bulldozers to cut a long defense line in an effort to control the blaze.

The fire has not yet threatened people or towns, Department of Natural Resources and Environment spokesman Michael Leonard told Victoria's Herald Sun newspaper, but it has taken hold in the Big Desert Wilderness Park in Victoria.

"The perimeter of the blaze continues to expand," Leonard said. "It will become a concern if the weather is really fierce.

Firefighters fear the wind could shift Tuesday, causing the first big fire of Australia's bushfire season to expand along an even larger front, threatening local communities.

"The rural properties are heavily grazed and the fuel load is low," Country Fire Service spokesman Scott Turner said, "so if the fire moves there, we can quickly move in."

Massive billows of smoke were visible from nearby communities over the weekend, at times so thick they forced the closure of a main road.

"It's created smoke clouds," said Bordertown police constable Tim McGregor. "It's amazing."

Officials warned that tinder dry conditions could cause the blaze to spread rapidly. The landscape, they said, has made it difficult to attack the fire.

"It is very dense, mallee scrub with a lot of undergrowth," said Turner. "Driving heavy fire fighting appliances in there is near impossible."

While no lives have been lost, the bushfire has been described as the biggest since the 1983 "Ash Wednesday" blaze which killed 75 people.