Final answer:
The incident would be categorized in the terrorism hazard category.
Step-by-step explanation:
The incident described, a truck explosion near a government building resulting in more than 100 casualties, would be categorized in the terrorism hazard category.
Terrorism refers to the use of violence or threat of violence by individuals or groups to intimidate or cause fear in a population and influence political, religious, or ideological objectives.
Examples of other incidents in this hazard category include the Oklahoma City bombing in 1995 and the 9/11 terrorist attacks in 2001.