What It Is
Terrorism refers to the use of force or violence against persons or property for purposes of intimidation, coercion, or ransom. A terrorist assailant might use everyday items such as firearms, knives, of vehicles; purpose-made weapons such as improvised explosive devices; or weapons of mass destruction such as toxic or poisonous chemicals, biological weapons, or radiological-release devices.
An active assailant is an individual actively engaged in killing or attempting to kill people, usually in a confined and populated area, and typically through the use of firearms. An individual may or may not have terrorist motives, and they may or may not have accomplices.