State police believe a Butler County woman killed in a head-on crash Monday night might been confused when she drove the wrong way on Interstate 279 in northern Allegheny County.

Amy Tua also may have suffered a medical emergency and knew she was in distress moments before the collision that killed the other driver.

About a mile from the crash, Tua, 45, of Lancaster Township had pulled off the highway and onto the median-crossover.

Just before or just after, she had activated the four-way flashers on her car.

“It’s a gray area. We don’t know why she turned onto that emergency crossover or why she turned on the four-ways,” Tua’s husband, 46-year-old Kenneth, said this morning.

“But it’s apparent something was wrong, and it seems like she was aware something was wrong.”

Authorities said Tua and Gary Helba II, 42, of Pittsburgh both died instantly of severe injuries in the wreck about 8 p.m. near the Camp Horne Road exit in Ohio Township.

For still unknown reasons, police say, Tua was driving north in the southbound lanes.

Investigators apparently do not suspect weather, road conditions or alcohol were factors in the accident. Speed did not appear to have a role either.

Tua’s speedometer needle reportedly was stuck at 55 mph, when police inspected the wreckage.

Autopsies determined she died of massive injuries to her head. Helba died of severe injuries to his body.

The results of routine toxicology tests probably won’t be known for several weeks.

Kenneth Tua said his wife of 16 years was taking prescription medication daily for an undisclosed health condition, however, he said her physician had placed no restrictions on her driving.

“She knew not to drink when on prescription drugs,” he said.

She also was familiar with the Parkway North, the name given stretch of I-279 where the deadly crash happened.

She drove it for 17 years, in and from work in Point Breeze. She was employed at the Allegheny County’s Children and Youth Service agency.