QUINCY (CBS SF) — Cal Fire has been deploying drones armed with ‘aerial firing devices’ igniting backfires in the battle to halt the advancing flames of the Dixie Fire, which had grown to 217,581 acres and was 23 percent contained early Wednesday.

At his Tuesday night briefing, Cal Fire Incident Operations Chief Mike Wink talked about the high-tech approach being to compliment the traditional air and ground efforts.

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“The last few nights, we have had drones that are able to carry firing devices, aerial firing devices, and do infrared flying so that the folks, the crews bringing the edge along Humboldt (Road), are able to use aerial firing devices through drones and have recon with infrared looking for spot fires, looking for where the heat is building, and making sure everything is going in a slow and controlled manner.”

“We don’t want to get too much heat in one area and not enough heat in another area. We can adjust that with all the technology we have available to us.”

Back firing or firing operations are used to clear out swaths of fuel in front of advancing flames. Without fuel, the fire will not advance with the same intensity.

A backfiring operation is being used along the northern and western edges of the blaze.

“We want to engage the fire where we want to on our terms,” Wink said.

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Damage assessment teams have also begun the task of confirming the toll in structures the fire has taken. While they are still early in the process they’ve found that 34 residences have been destroyed — several near Rich Bar.

Numerous homes also burned in Indian Falls and in the Paxton areas, but assessment teams have yet to canvas those communities.

Click to view interactive fire damage map

The fire has scorched nearly 340 square miles, an area bigger than New York City. While containment is growing each day, Wink said it will be a slow go because of the topography, particularly along the southwestern edge.

“There is difficult access to fire in that area,” Wink said at his Wednesday morning briefing. “Really rugged terrain. Heavy fuel. No access. So we are working on a multi-day plan.”

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Weather conditions have been trapping smoke over the blaze and the shade has helped lower temperatures and keep humidity up. But authorities said temperatures could warm up to well above normal in the second half of the week.