The National Transportation Safety Board (NTSB) announced Tuesday that the probable cause of a fatal January 2014 crash near Naperville, Ill., was a truck driver’s delayed reaction caused by fatigue and the poor safety behavior of a high-risk motor carrier.

One person died and two people, including an Illinois State Police officer, were seriously injured when a truck-tractor, operated by high-risk motor carrier DND International, Inc., struck emergency vehicles stopped in the right lane of Interstate 88 while assisting a disabled tractor trailer operated by another high-risk motor carrier, Michael’s Cartage.