On June 14, 2008, a 51-year-old male volunteer Assistant Chief (the victim) was fatally injured after being struck by a tractor-trailer. The victim was assisting at a motor vehicle incident that had been caused by near-zero visibility conditions. Unforeseen weather conditions had caused smoke from a contained fire on a nearby military range along with fog to move across the four-lane highway. A truck driver attempting to slow his tractor-trailer down after encountering the smoke and fog swerved suddenly to miss a vehicle parked in the highway striking a Sheriff's Deputy's patrol car before striking and killing the victim. A Sheriff's Deputy also lost his life and another was injured during this incident. Key contributing factors identified in this investigation include inability to establish traffic control on both sides of a divided highway, ineffective coordination of the multiple agencies involved in the emergency response, and unsafe vehicle operation of motorists during inclement weather and environmental conditions. NIOSH investigators concluded that, in order to minimize the risk of similar occurrences, fire departments should: 1. ensure that fire fighters responding to a scene involving a highway incident control oncoming traffic first, before responding to the emergency; 2. establish pre-incident traffic control plans and pre-incident agreements with law enforcement and other agencies such as highway departments. Additionally, Emergency Medical Services (EMS) should ensure that emergency vehicles are parked in protected work areas when responding to emergency situations. Additionally, municipalities should consider establishing a multi-agency communication system for response operations to coordinate and communicate incident activities. Although there is no evidence that the following recommendation could have specifically prevented this fatality, NIOSH investigators recommend that fire departments ensure high-visibility vests meet minimum requirements of ANSI/ISEA 107-2004 or ANSI/ISEA 207-2006.