From 1985 through 1989, 12,353 explosive incidents were reported. These statistics include the theft and recovery of explosive items and the use of explosives during bombings. The number of bombing incidents for the 5-year period from 1985 through 1989 totaled 6,592. Bombs can be made and delivered in a variety of ways. Secondary devices may be designed to inflict heavier casualties and added confusion. Bombs may be constructed with either manufactured or improvised components. An incendiary bomb is often used in arson, and this type of bomb is reported as arson rather than as a bombing. Further, bombings may occur in rural areas where no uniform reporting system exists, or they may be used by one criminal group against a rival group. Terrorists are not the only groups who use bombs. Bomb threats of activist groups, such as Earth First and the Animal Liberation Front, are becoming a larger problem. Some hard core criminals use explosives as weapons to gain access to buildings. Bombs are also frequently used to sterilize a crime scene. One of the biggest concerns of recent months has been safeguarding vulnerable public utilities and services against bombs. In addition, explosives are increasingly associated with drug trafficking. Vandalism is the largest single category of bombings, with 380 incidents reported for 1989. The second largest category of bombings involves revenge. The development and implementation of a bomb threat plan and procedures to follow during a bomb threat are detailed. The importance of security personnel training is stressed as well as fire prevention and containment.