The southbound lanes of the freeway were shut down, while the northbound lanes remained open, but were slow.
The fire started around 4 p.m. in light to medium brush, authorities said. It quickly doubled in size and impacted nearby power lines.
Water-dropping helicopters were called in and fire crews expect to be there overnight to fully contain the blaze. As of 7 p.m., 30 percent of the fire had been contained.
Two injuries were reported: an inmate in one of the crews suffered a minor injury and a firefighter had heat exhaustion.