LONE TREE, Colo. - A woman was hit and killed running across northbound Interstate 25 in Lone Tree early Sunday morning, police said.

The driver saw the woman running into traffic just north of Lincoln Avenue, but wasn't able to avoid hitting her, according to Kristen Knoll, spokesperson for the Lone Tree Police Department.

Medical personnel pronounced the woman dead at the scene.

The driver stopped and cooperated with the investigation. Police said the driver did not show any signs of intoxication and voluntarily provided a blood sample.

The driver was arrested for operating a vehicle without a valid driver's license.

Investigators are still working to confirm the identity of the victim.