SIOUX CITY &#8212 An “out of level” track caused a Labor Day train derailment that split Sergeant Bluff in half for more than two hours, railroad officials said Friday.

The derailment occurred just after 4 p.m. last Monday, when 16 railcars in the middle of a Union Pacific train slammed off the tracks. The derailment left the rest of the long train blocking all roadway intersections in Sergeant Bluff.

The official cause listed by Union Pacific inspectors was that the “geometry was out of place” on the track in that area, said company spokesman Mark Davis.

“It is easier to explain it as the track was out of level, which would have caused a railcar to lift and cause a derailment,” Davis said. “We don’t know how long it was like that.”

The tracks had passed a visual inspection earlier that day, Davis said, as well as a physical inspection on May 15.