Yosemite wildfire Scorches 144,000 Acres

A massive wildfire in northern California, scorching an area about the size of Chicago, has burned nearly 144,000 acres by early Monday.

The Rim Fire just keeps growing and is only 7% contained right now.

Encroaching its western end, the spread is threatening not only homes but also San Francisco's power supply.

“Thousands of firefighters are battling this massive blaze raging out of control in California's Sierra Foothills,” reports CNN's Nick Valencia.

Veteran firefighters are calling the blaze burning in and around Yosemite National Park one of the worst they've seen.

Vickie Wright of the U.S. Forest Service, PIO says, “So our main objective’s right now structure protection, just making sure we keep everyone safe and that we protect that park at all costs."

“Because of the steep terrain, parts of the fire are only accessible by air,” Valencia says. So bucket drops from aircraft is a crucial way that firefighters, taking shifts on the frontlines, are battling the blaze.

The Rim Fire has threatened small communities, including Groveland, located just on the outskirts of the fire line.

Evacuated by the fire, Susan Loesch and Curtis Evans wait for news about their vacation home.

"It was a little nerve-wracking when they came and knocked on my door, And then when we came up here yesterday morning it was very thick coming through the valley.  And then it cleared so I thought maybe we were still okay, so we're hoping,” Loesch says.

Follow along at CNN.com for developments.