When creating a contingency plan, police departments should take into account evacuation plans, pre-bomb and post-bomb cordons, other emergency services, and changing bomb-scene objectives. A thorough, well-rehearsed plan for coping with the aftermath of a detonation can help cities to reduce the effects of a bomb, ensure maximum public safety, and return rapidly to normality. In deciding whether to evacuate a building in the event of a bomb threat, decisionmakers should take into account the dangers of the bomb detonating in the course of the evacuation and when people are outside the building. A safer procedure might be to direct people to safe areas in the building, such as in subbasements. Public safety officials should consider warning mechanisms that can inform people in the bomb danger zone about the threat so they may seek a safer location. Piercing whistles used by police officers and pagers through which police inform security officers and building managers of bomb threats are useful. The chaotic aftermath of a bomb detonation presents different considerations. Damage from bomb explosions usually covers a vast area, necessitating both inner and outer cordons. The coordination of emergency services involves many agencies, including police, fire fighters, rescue workers, public works officials, and structural engineers. The police should control and coordinate the multiagency response. The police, in conjunction with local authorities, should educate business owners and building managers about procedures in response to bomb threats and help them to develop individual contingency plans and practice them.