Immediately below: a cool six-second time lapse of Mount Diablo as it burned Sunday night:

Here's a Storify collection of fire coverage this morning:

[View the story "Morgan Fire Burns East of Mount Diablo" on Storify]

***
Original post (5 p.m. Sunday): A wildfire that broke out earlier this afternoon near Morgan Territory Road southeast of the town of Clayton has burned about 300 acres in just three hours. Cal Fire reports the fire, burning in a relatively sparsely populated area near the eastern boundary of Mount Diablo State Park, is about 10 percent contained. Cal Fire says 50 to 75 structures are threatened. Contra Costa County authorities broadcast orders for an immediate evacuation for residents of the Oak Hill Lane and Curry Creek Road area. That's about 5 miles southeast of downtown Clayton.

#MorganFire [update] off Morgan Territory Rd, near Clayton (Contra Costa County) is now 300 acres & 10% contained. Evacuations in progress.

— CAL FIRE (@CAL_FIRE) September 8, 2013

Cal Fire also says that about 200 firefighters are on the scene, backed up by four fixed-wing air tankers and three helicopters. A webcam apparently positioned southwest of Mount Diablo shows the top of the peak enveloped in smoke, even though it's apparently several miles from where the fire is burning.

For historical context: Mount Diablo was the scene of a major wildfire in August 1977, when lightning ignited drought-parched chaparral and burned more than 6,000 acres on and around the mountain.

Comments on the Claycord community news site include this account of residents leaving the fire zone:

I called Camp 4 Paws at 5 PM to ask if they needed help evacuating the dogs. I was told that they were almost finished with getting all of the animals into vehicles and evacuate.

I saw a lot of trucks with horse trailers full of families and horses driving away from immediate fire area. Two family-filled trucks were carrying three horses in each trailer.

There are a lot of ranches and horses, dogs, burros, donkeys, goats, cats, chickens, alpacas, ponies, all pets in the area affected and one way in and one way out. My heart goes out to the families who are trying to leave safely with all of their loved ones.

Here's a long-distance shot of the fire posted on Instagram by user margaret_w:

claytonclayton

Firefighters Make Progress in Controlling Blaze East of Mount Diablo

Mount Diablo Blaze Grows Rapidly, Forces Evacuations