The single-vehicle crash occurred at about 5:35 a.m. just east of Interstate Highway 80 near the Laurel Street exit, according to CHP Officer Quistead.
The CHP issued a Sig-alert at about 5:50 a.m. since the big rig has blocked all lanes of the highway, Quistead said.
The CHP is diverting traffic from eastbound Highway 780 to both eastbound and westbound Highway 80 and then to Interstate Highway 680, which connects further east to Highway 780. Vallejo police are also assisting to control traffic through their city, Quistead said.
No injuries have been reported.