The CHP received a report at 6:40 a.m. of a Jeep being driven unsafely on Old Adobe Road, CHP Officer Dave Thomas said.
As the CHP was responding to the call, the Jeep collided with a big-rig at the intersection of Old Adobe and Stage Gulch roads, causing one of the vehicles to run into a power pole, knocking it over, Thomas said.
Both drivers were transported to Santa Rosa Memorial Hospital. PG&E is at the scene working to repair the downed power pole, Thomas said.
The intersection remains blocked and a fuel cleanup is under way because the contents of the big rig's tank spilled out onto the roadway, Thomas said.
He estimated the roadway would reopen around 11 a.m.
The cause of the accident is still under investigation.