BRAINTREE —  State police are investigating an early-morning crash on Interstate 93 in Braintree that left a 29-year-old woman dead.

According to reports from multiple media outlets, investigators say the Taunton woman, whose name has not been released, got out of her 2003 Buick Rendezvous on Saturday after she lost control and struck a guardrail while heading southbound. After striking the guardrail the car finally came to a stop in the right travel lane.

Police said the woman exited the vehicle when a 2005 Nissan Altima, also traveling southbound, slammed into the Buick. The Buick then slammed into the woman and killed her instantly.

The driver of the second car, a 20-year-old Brockton woman, was taken to Boston Medical Center to treat serious injuries. No charges were immediately filed.

Police are withholding the identity of the Taunton woman pending notification of family members.