WICHITA, Kan. (AP) — A Kansas Highway Patrol investigator says a truck driver failed to set the emergency brakes on a truck and likely caused an Amtrak train derailment west of Dodge City.

The Wichita Eagle reports the truck owned by Cimarron Crossing Feeders rolled downhill, broke through two fences, crossed U.S. 50 and struck the railroad bed. That displaced ties and tracks on the railroad where a train traveling from Los Angeles to Chicago derailed shortly after midnight March 14.

Six of the train’s 10 cars derailed, injuring 28 of the 144 people on board.

Technical trooper Herb Bradley wrote that the driver either didn’t set the truck’s parking brake or didn’t completely apply it before it rolled down the hill.

Damage from the derailment was estimated at more than $1.4 million.