The family, from Utah, were riding on Going-to-the-Sun Road when a number of rocks rained down from the mountain and onto their vehicle at about 7 p.m., according to a Glacier National Park release.
The rocks, ranging from “fist-sized” to “12-inches in diameter,” landed on the roof and shattered the rear windshield, the release said.
The teen’s parents and two other children in the vehicle were also injured in the incident.
Paramedics attempted to take the girl to a hospital, but she died on the way there.
Her parents, who suffered serious bruises, and the two other children were hospitalized.
Officials are withholding the victim’s name pending proper family notification.
In 1996, another person was killed by a rockfall on the same road, the release said.