Three people were killed after a multi-vehicle accident Tuesday afternoon on eastbound Interstate-40 near Williams. DPS says the accident involved a passenger car and two semi-trucks. Four people inside the car had to be extricated from their vehicle. Three of the four were killed, while the fourth was taken to Flagstaff Medical Center with serious injuries. The accident created at least a four-mile back up in the area when it occurred at around 2:30 p.m. The cause of the accident is under investigation.