It estimated the rocks were between fist-sized and 12 inches in diameter along with enough debris from the rockfall to fill the bed of a pickup truck. The incident happened near the East Tunnel on the popular and mountainous Going-to-the-Sun Road.
An ambulance that responded could not airlift the girl because of her unstable condition, the park said.
Flight paramedics traveled with her using ground ambulance to Kalispell, Montana. She died while being transported to a local hospital, the park said.
“The two adults suffered significant bruises and were transported to area hospitals. The two other children in the vehicle had minor injuries and also went by ambulance to the hospital,” the park said.
The victims were visiting from Utah, and authorities will release their names once family notifications are complete. Going-to-the-Sun Road was closed briefly Monday night while crew cleared the rocks and a tow truck removed the vehicle.
The last fatal injury from rockfall on the Going-to-the-Sun Road was in 1996 when a vehicle was struck, according to the park.