If the U.S. market follows the action of foreign stock exchanges, then we are in for some pain.
Expect tomorrow to be one of the worst days and this trend may continue for a week or so.
Wrong time to panic and sell. This could possibly be the worst time if you are long in the market and a good time to start looking at buying opportunities.
So, batten down the hatches, weather the storm and don't panic. Good luck.