I don't know if it was a terrorist
plot, or a disgruntled employee, or
a cruel coincidence.
But if it was a 'quiet' covert terrorist attack, it was probably
a "back-up operation" for those terrorists, just in case their hijackings had failed...Or it could be a follow-up attack.
If I were living in Florida I would be concerned.
I know you, Marcia, Kim Keller, etc...live and work in Florida
So I offer some suggestions that hopefully will not be needed; but
prudence and vigilance are necessary....
A LIST:

(1) Be careful what you buy in supermarkets.
(2) Obtain & store supplies of canned food, and other nonperishables.
(3) Purchase large stocks of concentrated bleach [preferably the
powder bleach; easier to store indefinitely]....BLEACH WILL KILL ANTHRAX SPORES that may settle on clothing, walls, floors, roofs, car exteriors, etc...!
(4) Avoid buying newspapers, tabloids, magazines for a while.
(5) Have your local US Postal Service
either hold off mail and parcel shipments, or else BUY a powerful
ULTRAVIOLET LAMP to kill bacteria
on mail that arrives at your door.
(6) Turn away strangers from your
frontdoor for the time being, regardless of how rude it seems.
(7) Bottled water is OK, portable water filtration systems are better.
(8) Related to # 6, purchase a legal firearm, if you feel you need to, so as to keep away suspiciously-acting strangers who you may feel pose a threat to your neighbourhood.
(9) Keep a handkerchief, soaked in "human safe" germicide, close by.
Disposable latex gloves a must, too.
(10) Keep a cellphone nearby, and keep up-to-date with the "latest" events
on the internet.

cheers.
Jacob