Emmylou Harris -- Investigated for Hit and Run

Emmylou Harris is now in the crosshairs of the L.A. County District Attorney for allegedly hitting a car on an L.A. Freeway and then hightailing it out of there ... TMZ has learned.

Law enforcement sources tell us ... the alleged incident occurred on October 1 at around 10:00 PM. They say Emmylou was driving a rental car on the 405 Freeway when she struck a car and took off without stopping or exchanging info.

We're told the CHP opened a hit and run investigation after the other driver filed a report. The investigation is now complete and we're told the file was sent to the D.A., who will decide if the country legend should be prosecuted.

Emmylou's rep acknowledges to TMZ she was involved in a "minor traffic accident," adding "she unintentionally rubbed bumpers with another vehicle." The rep says Emmylou didn't realize the cars made contact so she took off.

The rep calls it a "garden-variety accident that happens everyday on the 405," and Emmylou has turned the matter over to her insurance company.