The driver of the truck which killed them is charged with negligent homicide and negligent injuring.
State Police said the accident happened on La. 38 about 6 p.m.
A car driven by Elizabeth Pittman, 66, of Kentwood was stopped in the eastbound lane preparing to make a left turn into a private drive.
A 2007 Western Star 18-wheeler, driven by Stennis Taylor, 50. of Magnolia, Miss. was eastbound on LA 38 approaching the Lincoln from the rear.
Troopers said Taylor failed to see the Lincoln stopped in the roadway and attempted to pass the Lincoln on its left side to avoid a rear-end impact.
As the 18-wheeler, towing a wood chip trailer, crossed into the westbound lane of LA 38, the Lincoln began to turn left and was impacted on its left side by the front end of the truck.
Pittman and front seat passenger, Carol Gil, 75, were wearing seat belts and were airlifted from the scene with serious injuries.
The two rear passengers in the Lincoln, Lorina Smith, 74, and Catherine Simmons, 73, were not properly restrained at the time of the crash and were killed. Both were from the Kentwood area.
Taylor was wearing a seatbelt and received no injuries in the crash. He is charged with two counts each of Negligent Homicide and Negligent Injuring and was booked into the Tangipahoa Parish Jail.
Alcohol and/or drug impairment is not suspected to be a factor in the crash with toxicology results from each driver pending at the Louisiana State Police Crime Lab.