FURNACE CREEK, CA --- Two French teenagers were killed and five other French citizens were injured Aug. 22 in California's Death Valley, when the driver of their rented van fell asleep and the vehicle veered off the highway and rolled over. 

The crash happened on State Route 190 in Death Valley National Park, about 100 miles west of Las Vegas, the California Highway Patrol told the Associated Press. The victims were on a trip organized by a group based south of Paris called Cousins d'Amerique. At least three passengers were thrown from the vehicle when it rolled over. Only one of the passengers was wearing a seat belt. 

According to authorities, one victim was pronounced dead at the scene. The other passengers were taken to University Medical Center and Sunrise Hospital in Las Vegas. The van was traveling in a convoy of three vehicles. The van involved in the crash was the middle vehicle in the convoy. 

The 31-year-old driver of the rented passenger van admitted to being tired and falling asleep, said patrol Capt. Tim Lepper. 

The tragedy underscores the risks associated with driving while drowsy. The U.S. National Safety Council offers this list of warning signs that signal it's time to stop driving and check into a motel for the night:

• When your eyes keep closing or slip out of focus.

• When you yawn repeatedly.

• When you begin to feel especially impatient, irritable or restless.

• When you have trouble concentrating.

• When you can't remember driving the previous few miles.

• When you begin swerving into another lane or onto the shoulder.

• When you begin missing traffic signs, tailgating or driving too fast or too slowly.

• When you feel tension in the back, a burning sensation in the eyes or feel shallow breathing.