"A lot of pictures, clothes and the dog" are all one resident took.
Officials said firefighters were making progress, but they warned of high Santa Ana wind and low humidity during the day.
"The Santa Ana winds that blow out of the northeast and really push fires along died down overnight. The humidity went back up, and the temperatures dropped into the 50s, and that gave firefighters a chance to really spend some time lighting some backfires along a freeway here, which they're using as a fire break," reports , at the fire command center in Irvine Regional Park.
The homes in danger are west of the highway.
"Firefighters know that they're racing against time right now to do as much work as they can before the winds kick up again and start to push this fire inexorably toward the west where those homes are," Leitz said.
No residential damage had been reported, but homes were evacuated as a precaution, said Orange County Fire Authority spokesman Stephen Miller. A Red Flag warning, signifying a high fire danger, was in effect through Wednesday afternoon.
"The Santa Anas blow right through here and they're supposed to blow for another couple of days. That's the scary part. They can really get going," said Gary Treguboff, who lives in the Serrano Heights area of Orange.
There's plenty of fuel for the fire, reports Leitz.
"The fire started up in the Cleveland National Forest. Some areas of that wild land haven't burned for about 38 years," he said.
On Monday, fire crews stood guard in neighborhoods of Anaheim Hills and the city of Orange.
The thick smoke was "an ominous gray sign stretching more than 50 miles," reports KCBS-TV's Ross Palumbo.
"The ash was coming down like snow. I had all the windows and door shut because it was just overwhelming," said Kathie Scott, who was ordered to evacuate her Mayberry Ranch home.
The seasonal Santa Ana wind often plays a role in disastrous wildfires. In 2003, wind-driven wildfires destroyed more than 3,600 homes and killed 22 people in Southern California. The cause of the fire that was burning on Tuesday had not been determined.