BOULDER, Colo. (CBS4)– State troopers are investigating an early morning crash that killed two people and left another seriously injured.

The crash happened on Highway 287 early Monday morning.

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Troopers say a man and a woman in a truck were driving northbound on Hwy. 287 near Isabel when they crossed into the southbound lanes, striking a car.

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The two people in the truck were killed. Neither were wearing a seat belt. A woman in the other vehicle was taken to the hospital with serious injuries.

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Investigators believe drugs may be a factor in the crash. Those killed have not been identified.