Jay Hufford said he could see in the rearview mirror of his stopped car that the truck behind him was approaching too fast.
He pumped his brakes, hoping the flashing lights would alert the other driver and that he would slow.
Instead, the truck barreled into Hufford's Toyota Camry, killing Hufford's wife, Sue, 53, and mother, Sharon Hufford, 74, in the back seat.
Hufford saw them die, "as if somebody pulled the electrical plug."
"They just lost all animation, all life," he said. "I'm watching this in my rearview."
Hufford's father, Donald Hufford, 74, was severely injured in the crash at Highway 12 near Farmers Lane on Saturday evening.
The foursome was headed to the Villa restaurant off Montgomery Drive in Santa Rosa for dinner to celebrate Sue Hufford's 53rd birthday four days earlier. Her parents were to meet them there.
En route, Jay Hufford, 54, was approaching Farmers Lane on eastbound Highway 12 and was a few hundred feet back when he stopped behind traffic in the right lane to wait for a red light to change.
It was then he looked in his rearview mirror, saw the oncoming Sierra GMC pickup and "knew something bad was going to happen — the speed he was coming upon me."
"I could see him coming up, right up on me, and it's just a sick thing," Hufford said. "I'll never forget it."