If all you care about is the money then as soon as events such as this bombing happens, share prices fall and that's the time to buy shares. Apparently, if you work for a certain epartment in the government then it's also a good time to "bury bad news".
If you need to sell them and are only querying when to do so then anytime after the markets recover is OK.
I wouldn't sell them just because of the bombings. I don't see the logic in that one : keep them if at all possible.
On average shares outperform every savings account in the long term.