State Police said the accident happened about 3:30 p.m. at La. 308 and the La. 70 spur intersection.
Ernestina Llamas, 53, died when a truck driven by Melina Rodriguez, 63, of Raceland ran a stop sign and flashing red signal light and hit the passenger side of a car driven by Martina Llamas, 46, of Napoleonville, troopers said.
The victim was sitting in the front passenger seat.
The accident remains under investigation.