With this going on within 2 meters of their position you have to wonder why in hell they weren't pulled out. Kofi Annan and the UN are responsible for these mens deaths. This is gross negligence on his part.
They weren't pulled out because they were doing exactly what they were supposed to do. Aid and abet Hezbollah. And they were expendable. To the UN and Hezbollah, anyway.
"In response to a question about Hezbollah activity in the area, the official said that no Hezbollah activity had been reported there, with the nearest known activity by that group taking place at least five kilometres away" http://www.un.org/News/ossg/hilites.shtml