A loud explosion has rocked the Gaza Strip according to reports. It comes as Israeli tanks and troops have massed near Gaza for a threatened offensive against Palestinian militants.
Israel has said it will target Hamas leaders if kidnapped soldier Corporal Gilad Shalit is not freed.
In northern Gaza, Palestinians blocked roads with dirt and barbed wire. Militants with automatic rifles and anti-tank rockets patrolled the streets.
The US has urged Israel to give diplomacy a chance to win the release of 19-year-old Cpl Shalit, who was seized on Sunday by militants who also killed two soldiers in a raid on a military border post.
