Guardrail debris from a previous crash was to blame for a prison transport bus leaving the interstate and crashing into a moving train earlier this month near Odessa, Texas, the National Transportation Safety Board said Thursday.
Eight inmates and two correctional officers were killed in the crash.
According to the NTSB, the 225-foot-long metal guardrail leading up to an overpass was damaged in a vehicle collision the day before the prison bus accident.
Subsequent crashes caused by icy conditions moved portions of the guardrail onto traffic lanes.
The bus, westbound in the left lane, apparently struck the guardrail pieces, veered to the left and hit an embankment before becoming airborne.
At the base of the embankment, the bus continued toward the railroad tracks below the overpass, striking the 54-car train.
Five more people — four inmates and one staff member — were injured in the incident and hospitalized.
The bus was traveling from a prison facility in Abilene, Texas, to one in El Paso, Texas.