A line of investigators walk the blast zone looking for clues and evidence as to the cause of the explosion Sept. 28 on the Eglin Air Force Base range. The investigation was part of the FBI's large vehicle post blast school attended by state and local law enforcement agencies as well as Navy and Air Force explosive ordnance disposal technicians. Three vehicles were blown up to create the crime scenes that students would investigate. The week-long course was the second held on Eglin with 67 students representing 18 different U.S. agencies.