Crews responded to a 300-acre grass fire in Sunol, near 8501 Calaveras Rd., on the border of the Sunol Regional Wilderness reserve Friday.
No structures were in danger and there were no reported injuries.
The fire was 90 percent contained, as of 10 p.m., according to the Alameda County Fire Department, which expected to have the fire completely contained by Saturday.
Earlier, the smoke drifted away from I-680, according to California Highway Patrol.
It was two-alarm fire, according to Alameda County's Twitter feed. The affected area was east of I-680, near the Sunol Grade.
The crews employed 23 engines, two helicopters, one air tanker, three water tenders, four bulldozers and five hand crews, according to ACFD.
Units from Fremont, Livermore-Pleasanton, Cal Fire, East Bay Regional Parks and Hayward are either on the scene, or en route, according to Alameda County Fire Department.
The fire grew, according to initial reports, from six-acres to 300-acres in about an hour.