http://www.bbc.co.uk/sport/0/formula1/18201521 Seems strange, apparently it's the 2nd year in a row the bomb squad have been called in. So F1 can travel to Bahrain, and the race weekend is largely safe, yet Monaco causes issues?
There was a massive fire in Spain as well. Maybe they should have all the races in Bahrain just to be on the safe side.
To be serious though, both these cases could be linked, maybe revenge for the Bahrain GP go ahead? Not just one person, maybe a group planning a series of attacks, or am I just being a scaremonger.
Turns out it was a teams electrical wiring that got blown up. Someone had left something behind by mistake, the bomb squad overreacted.