The California Highway Patrol says that drugs and/or alcohol are believed to be a factor in the crash in the area of Avenue 13 and Road 23 on December 31.
Officers say the driver of a Honda CR-V was going west on Avenue 13 when they ran the stop sign and crashed into the side of the big rig.
The vehicle veered off to the shoulder and flipped over.
Officers say three men and one woman were thrown from the Honda.
Two people were declared dead at the scene, and three others were rushed to the hospital with major injuries.
Officers say the driver of the big rig was not hurt.
The two people killed have not been identified.