FRANKLIN PARK, Allegheny County — Accident reconstruction specialists continue to investigate the fatal wreck south of the Wexford exit on Interstate 79 that caused a miles-long traffic jam on Wednesday.

A Butler County woman was killed in the afternoon head-on crash on I-79, state police said.

Diane C. Spuntak, 52, of Adams Township was a passenger in a northbound car that crossed the highway’s grass median about 3:40 p.m. and collided with a sport utility vehicle traveling north, according to a police report.

Spuntak was pronounced dead at the scene at 4:19 p.m.

Spuntak’s live-in boyfriend, James P. McGuigan, 58, who was driving the car, and the SUV driver, Brenna Halbedl, 25, of Oakdale, Allegheny County, were seriously injured.

Both drivers were taken to Allegheny General Hospital, and their conditions were not known this morning.

Halbedl’s infant daughter, who was in a child safety seat, was not injured.

Police do not know what caused McGuigan to lose control of his 1997 Oldsmobile Cutlass Supreme as it traveled north in the center lane.

The crash closed the inbound ramp at the Wexford interchange for more than an hour.