2 teens killed in head-on crash were just about to start senior year at Castle View High School

Mangled car parts and a damaged guardrail are all that remains of a deadly crash on a frontage road south of Castle Rock. According to the Colorado State Patrol, a vehicle carrying four teenagers was struck head-on Friday just before midnight by an oncoming car. Audrey Todd and Colton Bellamy were killed. Both were 17.

The driver who hit the vehicle they were in was arrested. He was identified as Ricky Avalos-Trujillo.

"The driver of the car that struck the Honda was transported with minor injuries but ultimately.. after being medically cleared was taken into custody on suspicion of driving under the influence of alcohol," Colorado State Trooper Josh Lewis said.

While it's early in the investigation, Avalos-Trujillo tentatively faces two charges of vehicular homicide, vehicular assault and DUI.

"Anytime somebody makes the decision to get behind the wheel under the influence -- regardless of what the substance is -- it's a selfish decision," Lewis said.

Several people who knew Todd and Bellamy described them to CBS News Colorado as both being active students who were set to start their senior year at Castle View High School in Castle Rock. It was their final weekend before returning to class.

While Lewis says that suspect is innocent until proven guilty, there's no question what happened was an avoidable tragedy.

"It's a life-changing, a life-ending decision. There's simply no reason for it," he said.

The other two teenagers in the Honda were also taken to the hospital, one with minor injuries and the other with serious injuries.

In a letter to the students, staff and parent community, Castle View High's principal says they are reevaluating the schedule for their first week of school starting Monday. They will have crisis counselors at the school who will be available for all students.

UPDATE: Ricky Avalos-Trujillo formally charged in crash that killed 2 Colorado high schoolers