On their third day of fighting an ever-growing fire in a stand of pine trees, firefighters saw little relief from a rainstorm that crossed a small portion of the city.

The storm passed over the city far north of the fire, which has burned about 85 acres so far in the 7100 block of Gates Road.

Both city firefighters and the Virginia Department of Forestry agree that lightning is the most likely cause of the fire.

“We think it was a lightning strike,” said Jeff Darr, a forestry service firefighter.

Battalion Chief Chuck Knight concurred, saying that fires in such remote areas among tall trees are typically the result of lightning. The fire was first noticed Wednesday evening. A lightning storm had moved through the area a day or two before that, he said.

“That’s about the right time frame,” Knight said.

Firefighters established a fire line around the fire on Wednesday night, but it jumped the line on Thursday. Firefighters established a new line and also set their own fires to burn off fuel.

“We’re working hand in hand with the forestry service,” Knight said.

Department of Forestry firefighter Toni Noreika said the burned land formerly belonged to International Paper. She does not know who currently owns it.

Fighting blazes in the woods is not the same as combating a structure fire. With any fire in a building, firefighters will be on the scene until it is extinguished.

However, it is impossible to do that with a wildfire, Knight said.

“With something like this, you contain it and let it burn itself out,” he said.

Wildland firefighters typically do their jobs by establishing barriers for the fire and by setting their own fires to eliminate the fuel. The firefighters plow lines around the fire and use natural barriers like roads and creeks to contain it. They also sometimes set their own fires on the same side of the fire line and allow it to burn back to the wildfire.

Once the barrier is established, the job is simple — monitor the lines and hope for rain.

“The plan today is monitoring the situation,” Knight said. “We need some rain. A good day or two of soaking rain will benefit everybody.”

The heat also has caused problems for the firefighters. Some personnel were treated on the scene Thursday for heat exhaustion.

“The heat takes a toll on anything that you do,” Knight said. “It really does take a lot out of the guys very early on.”