The fire was first reported at 12:13 p.m. on a steep hillside near Mountain Boulevard and Edwards Avenue and prompted the evacuation of about 50 homes threatened by the fire.
VIDEO: Fast-moving fire threatens dozens of homes in Oakland Hills
The homes are on Bayview Drive, Skyview Drive, Ridgemont Drive, Viewcrest Drive and the 13650 block of Campus Drive, Oakland police said shortly after 1 p.m.
Merritt College at 12500 Campus Drive was also evacuated and classes have been canceled, according to the school's website.
Cal Fire spokeswoman Pam Temmermand said shortly after 2 p.m. that the blaze is considered 50 percent contained but that the homes are no longer threatened since there are no active flames on the hillside.
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A couple of helicopters are continuing to drop water where needed and crews are "working on the left flank of the fire," Temmermand said. She said crews will likely be at the scene for several hours.
No injuries were reported in the blaze and no structures were damaged.
"Oakland fire jumped on it really quick," Temmermand said.
With the help of Cal Fire and other assisting agencies, "we were able to get a handle on this fairly quickly so that's good news," she said.
The California Highway Patrol has shut down off-ramps on eastbound Highway 580 at Keller and Edwards avenues to keep traffic away from the firefighting effort.
The National Weather Service issued a red flag warning today through Wednesday afternoon for the East Bay hills because of dry weather conditions that pose a high risk of wildfires.