One person is dead after the semi-truck he was in, left westbound Interstate-40 and crashed Wednesday night west of Flagstaff. DPS says the accident happened at around 11:25 at Exit 191, near Naval Observatory Road. Authorities say when the truck went off the interstate it went over the concrete barrier wall before falling onto the road below. The driver of the semi was wearing his seat belt at the time, but he was pronounced dead at the scene. No other vehicles were involved in the accident and the name of the driver has not been released.