Freight trains collide in Arkansas Updated: Monday, August 18, 2014 ARKANSAS (NEWSCHANNEL 3) - Investigators are looking into what caused a deadly accident after two freight trains collided in northeast Arkansas.State police say two Union Pacific train crew members were killed and two others were injured when the trains collided Sunday morning."I heard a noise that sounded like a thunderstorm. I realized it was something more than that when it got louder and we got to the highway and realized it was a train crash. I heard two guys hollering for help," said one witness. The accident caused a fire that took crews seven hours to put out.Many were evacuated from their homes for a few hours over fears of hazardous materials on board.The National Transportation Safety Board will be on scene this week to look into what caused it.Investigators say they want to know why two trains were on the track at the same time.