It happened around 8:45 p.m. Friday on Route 78 in Lower Macungie Township, Pennsylvania.
Police said 29-year-old Tara Slamon's Honda hit the center median. She got out of her car to seek help when she was struck by a GMC Envoy.
The vehicle then struck two other people who had pulled their Jeep Cherokee over to the right side of the road to assist Slamon with the earlier accident, police said.
Slamon was rushed to Lehigh Valley Hospital where she was pronounced dead Saturday morning.
The driver and passenger of the Jeep were treated and released from the hospital.
Pennsylvania State Police are investigating.
So far, no charges have been filed.