By Nidal al-Mughrabi 1 hour, 30 minutes ago GAZA (Reuters) - Masked gunmen stormed into a club for United Nations workers in Gaza City on Sunday and blew up the drinking hall in a new sign of spiralling unrest ahead of a Palestinian election. It was the first such attack in Gaza on a U.N. target and came against a backdrop of growing unease among foreigners. Just over one day earlier, a group freed three British hostages that had been seized to demand foreign pressure on Israel.