The California Highway Patrol says it happened on Santa Fe Drive and Avenue 2, just east of Atwater.
Officers say a white vehicle hatchback with a man and woman inside was traveling southbound on Santa Fe, and a pickup truck was also traveling northbound on Santa Fe.
For unknown reasons, the truck crossed over into the southbound lanes and hit the hatchback head-on.
At least one person died.
Two others were taken to a nearby hospital, and their conditions have not been released.
It is not known if drugs or alcohol were factors in the crash.