A motorist died in the Mount Vernon area Friday morning following an argument with another driver, but the cause of the woman’s death is still under investigation, Fairfax County police said.

Police responded to the report of a woman lying in roadway in the 7100 block of Harrison Lane around 11:30 a.m. Friday, police said.

A 21-year-old woman, who was driving, had gotten out of her car and began a discussion with another driver in traffic, police said. There appeared to be an altercation between the two, police said. They said it was not clear whether the two knew each other, or what the argument was about.

It was not immediately clear how the woman was injured, police said. They said preliminary reports indicate she suffered trauma to the upper body.

“It is under investigation whether road rage was involved,” said Lucy Caldwell, a police spokeswoman.

The other driver, who was in a black Chevrolet SUV with temporary tags, drove away, police said. Officers are still looking for that driver, police said.

The woman was taken to a local hospital, where she died, police said.

Police said they are withholding the woman’s name, pending notification of next of kin.

A third driver, who was in a light-colored SUV, was also involved in the incident and remained on the scene and was being interviewed by detectives, police said.

Virginia’s Office of the Chief Medical Examiner will determine the cause and manner of the woman’s death.