MARBLE CANYON, Ariz. (AP) -- Three members of an Allen, Texas, family were killed when their van collided head-on with a car on a highway in a remote area of northern Arizona Tuesday afternoon. The Arizona Department of Public Safety identified those killed as 60-year-old Rebecca Simpson Stryker, 56-year-old James Lee Stryker and 16-year-old Travis Stryker. A twin brother of the teenager, 16-year-old Austin Stryker, was seriously injured and hospitalized in Flagstaff. The DPS said a car that crossed the center line first collided with a second car before it collided with the Strykers' van. The DPS said two people in the car that crossed the center line also were injured. The accident occurred on US 89A near the Vermillion Cliffs National Monument. The DPS said cause of the accident is under investigation.