The British Foreign Office has issued a travel warning to Westerners who might be in Benghazi, urging all its citizens to leave the city immediately. The advisory warns of a "specific, imminent threat to Westerners in Benghazi" and urges Britons to avoid all travel in Libya, outside of a handful of major cities, and even then travel should be limited to "essential" business. Though it is address to British citizens, presumably all foreigners should be considered in danger.
The latest warning goes beyond the usual caution about foreigners in a dangerous area, saying there is "high threat" of terrorism, kidnapping, and other "retaliatory attacks" against Western targets. The notice warns British national to "keep a low profile," avoid crowds and large gatherings, and stay indoors at night. It also specifically mentions the French adventure in Mali as a reason to be concerned about retaliation.
Their last built of advice is just a good practical measure for any overseas journey, but feels particularly ominous after reading the whole thing:
You should take out comprehensive travel and medical insurance before travelling.