The California Highway Patrol was responding to reports of a crash Friday along Highway 101 in Paso Robles involving an SUV and big rig.
It happened at about 4:23 p.m. in the northbound lanes of the highway near the Spring Street offramp.
CHP reports as many as four vehicles may be involved.
No word on the extent of any injuries but an ambulance has been requested at the scene.
Officers are asking drivers to be care if they are planning to drive through the area.