The Westbound section of the interstate reopened around 9:30 p.m. Sunday evening. The Eastbound side remains closed.
The blaze is 25 percent contained, according to officials, and firefighters are making further progress.
The highway is closed from North Flynn Road near Livermore to Grant Line Road near Tracy, according to the California Highway Patrol.
Fire officials said at 6:40 p.m. that there is no visibility in the area due to thick, black smoke. No injuries have been reported.
A Sig-alert was issued at 6:29 p.m. and there is currently no estimated time of opening, according to the CHP.