Law enforcement authorities are looking for the driver of a vehicle that struck a 19-year-old Boulder woman and fled the scene.

The collision occurred about 1:20 a.m. Tuesday as the woman was walking across U.S. Highway 287 north of Longmont.

Officials say the motorist failed to stop and render aid, and drove away instead.

The victim was airlifted to Denver Health Medical Center, where she was pronounced dead.

Her name has not been released.

Investigators say it's unknown whether drugs, alcohol or excessive speed were factors in the collision.