Emergency management officials from central Ohio and the state are participating this week in a training exercise that simulates the responses to a terrorist attack. The Ohio Emergency Management Agency and Franklin County Emergency Management and Homeland Security are among the groups taking part in the exercise. The exercise includes an imaginary nuclear explosion in Columbus and involves about 5,500 military staff and civilians. They'll practice search and rescue missions, decontamination operations and hypothetical medical treatments, among other activities. The exercise includes teams from the Department of Defense and the Federal Emergency Management Agency.