SIERRA MADRE, California (CNN) -- A wildfire that has burned 490 acres of dry brush in the Southern California mountains has gained ground, authorities said Monday.
The blaze in the San Gabriel Mountains broke through containment lines during the night, reducing containment to 23 percent from 30 percent on Sunday, according to the U.S. Forest Service.
About 1,000 people have been evacuated from about 400 structures near the wildfire, authorities said.
One small building has been damaged.
The blaze began Saturday in an area that has not seen fires in more than 30 years.
That lack of activity means it has a great deal of kindling such as dry brush and shrubs amid fallen leaves and branches to fuel the flames, authorities said.
The terrain also is rugged, hampering firefighters' efforts.
About 580 firefighters are working to extinguish the flames. Four injuries have been reported among the firefighters, officials said. Watch firefighters battle the blaze »
A wedding party of about 50 people woke up the morning after the nuptials to find search-and-rescue officials telling them to evacuate Sunday.
"It was sort of shocking. I didn't think that we were going to have to be airlifted out," the bride, Julie Grady, said. Watch the couple on their eventful weekend »
Authorities said the blaze was manmade but they did not know exactly what caused it. E-mail to a friend
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