Israel imposed a total siege on the Gaza Strip Monday and cut off the water supply as it kept bombing targets in the crowded Palestinian enclave in response to the Hamas surprise assault it has likened to the 9/11 attacks.
Reeling from the Islamist group's unprecedented ground, air and sea attacks, Israel has counted over 700 dead and launched a withering barrage of strikes on Gaza that have martyred 560 people there.
The skies over Gaza were blackened by plumes of smoke from deafening explosions as Hamas kept launching rockets as far as Tel Aviv and Jerusalem, where missile defence systems fired and air raid sirens blared.
Hamas -- whose fighters surged into Israeli towns on Saturday, spraying gunfire at civilians and dragging off about 100 hostages -- claimed on Monday that Israeli air strikes had killed four of the captives.
Israel said it had called up 300,000 army reservists for its "Swords of Iron" campaign, and truck convoys were moving tanks to the south, where its forces had dislodged the last holdout Hamas fighters from embattled towns.
"We are in control of the communities," said military spokesman Daniel Hagari, cautioning that some of them may remain after about 1,000 Hamas fighters had swarmed into the region on the Jewish Sabbath.
Defence Minister Yoav Gallant said Israel would impose a "complete siege" on the long blockaded enclave and stressed what this meant for its 2.3 million people: "No electricity, no food, no water, no gas -- it's all closed."
Palestinians in the impoverished coastal territory braced for what many feared would be a massive Israeli ground attack aiming to defeat Hamas and liberate the hostages.
Israel Prime Minister Benjamin Netanyahu has warned Gaza civilians to get away from all Hamas sites, which he vowed to turn "to rubble".