An aggressive attack is underway on a new fire start north of Durango.

U.S. Forest Service spokeswoman Esther Godson said a ¼-acre fire was spotted east of Shalona Lake, about 16 miles north of Durango, in the Bear Creek drainage.

The blaze has been named the “505 Fire.” Fires started on National Forest lands are first assigned a number name. But if a fire grows and requires an extended response, it will be assigned a name, Godson said.

As of Thursday afternoon, an aerial attack, including a helicopter and a large air tanker, was trying to douse the blaze. An engine and a 20-person hand crew were en route, but it was expected to take a while to hike to the burn area, Godson said.

Godson said fire crews won’t know what sparked the blaze until they reach the burn area.