A trip home from California ended in tragedy for a Littleton family on July 13, when a semi-truck caused an inexperienced driver to over-correct the vehicle just east of Rock Springs, Wyoming.

“It was your standard roll-over accident,” said Wyoming State Patrol Division Lt. Scott Keane.

“Yet it was one of the worst we’ve seen here. It totally annihilated a family in a matter of seconds.”

Dodi Arnold, 45, and her two daughters, Kinni, 24, and Bailey, 15, were killed. Jonathan Arnold, 43, the fathe,r and daughter Dellen Arnold, 16, were treated for injuries and then released from a hospital. The driver of the semi was not injured.

Dodi and Bailey weren’t wearing seatbelts. Kinni appeared to be wearing hers, but was wearing it improperly.

Dellen was driving the family’s 2009 Chevrolet Suburban around 7:15 p.m. when a semi-truck began to change lanes, Keane said.

It’s possible she was in the truck’s blind spot, Keane said, meaning that the Arnolds’ Suburban might not have been visible to the truck driver.

“We’ll never know,” he said.

Once the semi changed lanes, the Suburban’s right tires were shoved to the inside of the rumble strip.

“She was taking out a delineator post as she went,” Keane said.

An experienced driver may have been able to maneuver the vehicle away from the semi and back onto the road, but the 16-year-old most likely had problems controlling the full-sized Suburban, he said.

She jerked the wheel and over-corrected. Drugs, alcohol and speed were not factors, according to Keane. The vehicle was going 80 miles-per-hour.

The semi-truck driver had a clean record, according to Keane. He had not logged an abundance of hours and he was an experienced driver.