20 acre brush fire in Sunol Regional Wilderness

ALAMEDA COUNTY, Calif. -- A 20-acre brush fire is burning near the Sunol Regional Wilderness this morning in Alameda County, according Cal Fire.

Firefighters responded to the fire at about 4:30 a.m. near Geary and Calaveras roads, Alameda County Fire Department spokeswoman Aisha Knowles said.

Knowles said it's possible more than one lightning strike started the fire, which multiple people reported. So it could have started in more than one location, she said.

Firefighters are working in heavy brush and firefighters had the fire 20 percent contained as of about 8:50 a.m., a Cal Fire official said.

She said firefighters do not know when the fire will be 100 percent contained.

No structures have been burned nor are any threatened, Knowles and the Cal Fire official said. No firefighters have been injured, according to Cal Fire.