An internal chemical attack is one in which the chemical agent is released inside a building, event, or security perimeter. In such scenarios, the threat device or material is either brought into the event or is hidden in the event venue ahead of time.
Internal attacks can be harder to perpetrate because they usually involve overcoming some degree of security countermeasures, such as screening and searching. However, in general terms such attacks require smaller devices and/or less material to have an adverse effect because the perpetrators are closer to their target.
This scenario occurs at a political-party convention. It is the same scenario as described in the “Anthrax Letter” scenario. The convention is now underway. You are on the incident-command team in the episodes to follow. Searches of the venues were conducted, and screening of all people attending the event is now underway. The venue search focused primarily on searching for explosive devices and did not find anything unusual. The personnel screening is focused on conventional threats, such as knives and firearms.
As with the “external attack” scenario, the episodes here may be serious enough to stop the event in its tracks. Therefore, the episodes are three different standalone scenarios. The identity of the threat chemical will be unknown to responders at the outset of these scenarios and will need to be discovered by the scenario participants.