In yet another front in the war on the unexpected, more amateurs are joining the fight against terrorism:

Unlike police, firefighters and emergency medical personnel don’t need warrants to access hundreds of thousands of homes and buildings each year, putting them in a position to spot behavior that could indicate terrorist activity or planning.

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When going to private residences, for example, they are told to be alert for a person who is hostile, uncooperative or expressing hate or discontent with the United States; unusual chemicals or other materials that seem out of place; ammunition, firearms or weapons boxes; surveillance equipment; still and video cameras; night-vision goggles; maps, photos, blueprints; police manuals, training manuals, flight manuals; and little or no furniture other than a bed or mattress.