Drivers on central Florida's primary urban corridor, Interstate 4 in Polk County, encountered a blinding mixture of smoke and fog that crept onto the roadway during the early morning hours of 9 January 2008. Seventy cars and trucks collided near mile marker 55 resulting in five deaths and 38 injuries. Sheriff Grady Judd of Polk County described the conditions as “a wall of smoke and fog.” Although fog was in the area, it was the addition of fine smoke particulates that abruptly dropped the visibility to zero. The dangerous smoky conditions were the result of a nearby prescribed burn that escaped containment. The prescribed burn was started the previous day just 2 km from the crash site and went out of control when the relative humidity dropped well below what was originally forecast from an automated system. Control was regained before sunset but smoldering and spot fires occurred overnight as fog began to develop. Caution signs were erected along the interstate connecting the major urban centers of Tampa/St. Petersburg and Orlando and the Florida Highway Patrol made occasional passes through the area. Blown by light easterly winds, the blanket of smoke meandered across flat terrain of varying vegetation then crept south along a hill and drained over the highway just after 4 am. Soon after, the carnage occurred. As with most accidents many events converged. The prescribed burn went out of control and was much larger than expected. Microscale processes affected smoke migration. Effective methods to monitor smoke and visibility were lacking. Ultimately, drivers were unaware of the combined smoke and fog density and the rapid drop in visibility. Unfortunately, five other similar and avoidable accidents involving 72 vehicles have occurred in Florida since the year 2000 leaving 12 dead and 52 injured. To avoid another similar mishap several courses of action exist. Automated forecasts for prescribed burns should have some level of human oversight, particularly when near the urban interface. When fires are near urban thoroughfares, smoke management tools or other high resolution modeling could be used to indicate microscale circulations that may carry smoke in unexpected directions and impact smoke sensitive areas. This event was beyond the resolution of effective satellite monitoring but in-situ monitoring was possible with portable visibility sensors reporting to the National Weather Service, Highway Patrol, and ultimately to roadway signage. When visibility sensors are not available, human roadway observations spaced at short intervals would help avoid a repeat. Information saves lives.