Let's just say this--heads up routinely, folks. Anything looks likely able to cause mayhem, check it out and deal with it accordingly.
FREEPERS are good at showing they put their umph where their mouths are over and over again. Sounds like our nation needs our eyes, ears and alert actions as never before.
And, again, it's probably wise to already have at least a nodding acquaintance with some trusted enforcement officials who would have the authority and presence of mind to take action. No use calling up any official in any agency only to have it buried out of ignorance, too many calls or not knowing you nor trusting your observations. . . .though calling and taking that risk would probably be wiser than not calling.
And be wise as serpents and overtly harmless as doves. No need risking a FREEPER'S LIFE because you said the wrong thing in the wrong way at the wrong time in the wrong situation.
In some situations, it might be wise to say something neutral or agreeable sounding just to protect yourself until you can leave the scene, WRITE YOUR OBSERVATIONS UP and get them to someone trusted.
When you fininsh your observation--taking notes as fitting or recording in a walkman or a cell phone's memory--ISOLATE YOURSELF AND WRITE UP YOUR OBSERVATIONS AS QUICKLY AND ACCURATELY AS POSSIBLE. DATE AND TIME THEM.
WRITE BEHAVIORALLY--PERSON "A" IN XYZ CLOTHING WITH X IN THEIR HANDS RAN FROM __________ TO A LATE MODEL DARK BLUE CAR WITH LICENSE NUMBER__________ AND RACED OFF DOWN ___________ ROAD AT AN ABOVE AVERAGE SPEED GOING SOUTH ON THE NORTH/SOUTH STREET.
That is, describe actions first and foremost and completely. Only then can you go back and describe your feelings about what you were observing. Your feelings can be valuable input but the actions of the observed are far more important.
Your feelings probably come from or are connected to your intuition. Your intuition probably tunes in on many very subtle cues unconsciously and holistically rather than linear-logically. That can be very valuable--particularly if your intuition is often right.
If you think the issue is urgent, then turn the report in, fax it ASAP to your enforcement contact. If not, you might have fitting people who have good perspective on such things to review it with you first.
If you have a small camera, keep it with you. You might put in at least 400 ASA film if there's a likelihood of even significant darker scenes in your normal daily activities. If you always work etc. in bright daylight, a slower film would be good for the increased resolution.
If it's urgent, you can turn the film over. . . . but make some judgements here. If you turn the film over, you may never be compensated. . . . lose all control over it and the images etc. Remember Kennedy's death and the movie. . . . though he did get a pretty price for it eventually. If reasonably practical and not so urgent, you might consider taking it to a trusted quality photoshop and wait for it to be developed. Then get triplicates. Ask a trusted friend to file one in a safety deposit or other very secure location unknown to you. Tell 2-3 trusted unconneced, unrelated people who that person was with the photos.
If you have a digital camera, make several backup files on CD-ROM MEDIA even if you have to go to a friends to use their CD burner. Stash a copy safely yourself and 2-3 with trusted people. Probably officials would like the original digital file but copies are really about as good. On film photos, they will insist on the original negatives. You can still put a (C) notice on the edge or corner of the best shots with a very small drafting ink pen with drafting black ink available at all office supplies. (C) 2001 and your name or identifier would do.
For FREEPERS who are normally housebound but with ample window space to watch goings on in popular public places, you might keep a journal of the daily routines. If something radically or significantly out of ordinary occurs, you'll have a record and know better when to call the officials and how fast.
If middle eastern looking men seemed to be manically driving a vehicle into a key building or large group of people, an urgent call might be in order. Having a phone with a panic button to the trusted official might be in order. If such people put parcels down in a crowded market place and seemingly make haste to leave, urgent action might also be in order. But a record of the routine days for the area can give you a baseline to make those judgments better against.
Perhaps others hereon can critique the above and add their own ideas/suggestions.
Too bad action couldn't be made before this point. It's not going to do the people about to be killed much good.
To arms, to arms, the terrorists are coming! 
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