Seven people, including three Craig teenagers, were seriously injured early Sunday when the car they were riding in rolled down an embankment off U.S. Highway 40 about two miles west of Hayden.
Alcohol and drugs may have been involved, investigators said.
At about 12:23 a.m., a 1995 Ford Taurus traveling west near milepost 105 skidded off the south side of the road, traveling down an embankment and vaulting about 50 feet before rolling into a group of trees, the Colorado State Patrol reported.
There were nine people in the vehicle, four in the front seat and five in the back. None of them was wearing seat belts.
Eight people were transported to area hospitals. A 16-year-old girl from Hayden was flown to St. Mary's Hospital in Grand Junction where she was in critical condition Sunday.
Troopers declined to release the girl's name because of the seriousness of her injuries. Her birthday was Saturday.
The driver of the vehicle, 23-year-old Tomas Marquez of Hayden, and Chase Beach, 18, of Hayden also were taken to St. Mary's Hospital, where they were listed in serious condition Sunday.
Brandon Ricker, 21, of Hayden and Levi Heythaler, 17, Sarah Coyner, 16, and Chelsea Merrill, 16 -- all of Craig -- were in stable condition at Yampa Valley Medical Center.
Marleen Grubbs, 17, of Hayden was treated at the hospital and released Sunday morning.
Another passenger in the car, 15-year-old Dustin Jones of Hayden, walked home from the accident with cuts and bruises.
Marquez first was taken to The Memorial Hospital in Craig where trooper Ryan Parker said he noticed a strong smell of alcohol coming from Marquez's breath.
Marquez also had bloodshot eyes and slurred speech, trooper Rick Kaspar said.
Marquez refused a Breathalyzer test but later submitted to a blood test.
The results were sent to the Colorado Department of Public Health and Environment and should be available in about two weeks.
Marquez admitted to Parker that he drank alcohol before he drove and told troopers he smoked marijuana five to six hours before driving and smoked methamphethamine earlier Saturday, Kaspar said.
Charges are pending the conclusion of the investigation.
Kaspar estimated the vehicle was traveling about 80 miles per hour at the time of the crash.
Though the car is in bad shape, the occupant compartment was intact, leading Kaspar to speculate that if they had been wearing seatbelts, the occupants would have been a lot better off, he said.
In Colorado, it's against the law to have more than three people in the front seat of a vehicle.
Those who are 16 and younger are required to wear a seat belt, but there is no state law against having more people in a vehicle than there are seat belts available, Kaspar said.