A California wildfire is threatening to sweep through an ancient grove of Giant Sequoia trees.

Lightning strikes on July 31 sparked the wildfire. It has charred 172 square miles, growing by nearly 40 square miles in the last week.

In a fight to save the trees, firefighters have been clearing lines with bulldozers around the Grant Grove and putting up sprinklers, said Andy Isolano, a spokesman for the Clovis Fire Department.

The grove is named for the towering General Grant tree that stands 268 feet tall. There are dozens of Sequoia groves in the Sierra Nevada, and some trees are 3,000 years old.

Although Isolano said the trees can endure fire, some are stressed by the four-year drought. The flames are also just a few miles from the grove.

Fresno County Sheriff's deputies were going door to door Friday distributing mandatory evacuation notices to residents in the tiny community of Dunlap, east of Fresno. About 130 people live in Dunlap, but it wasn't clear how many residents will need to leave.

On Thursday, officials from Kings Canyon National Park ordered the evacuation of all Sequoia National Forest park visitors and park employees, concession staff and residents of Wilsonia in the Grant Grove area of the park.

Also, in Northern California, a wildfire that exploded in size has charred 50 square miles and destroyed six homes in Amador County. Evacuations remained in place Friday, Cal Fire officials said.