An Amtrak train headed from San Antonio to Chicago collided with an 18-wheeler blocking the tracks near Mesquite, killing the truck driver. According to NBC DFW, the Dallas County Medical Examiner's Office identified the truck driver as Shannon Thomas of Plano. Thursday, delaying Train 22, the Texas Eagle, at the scene for 5 1/2 hours, an Amtrak spokesman said. One passenger was checked by emergency medical responders at the scene but remained on the train, he said. A spokeswoman for the Dallas County Sheriff's Office told the station that it was unclear what had caused the accident, which remained under investigation.