A surprise assault launched by the Palestinian militant group Hamas over the weekend has killed hundreds in Israel but also precipitated mass mobilisation among Israelis who have found a renewed dedication to their national cause.

Israel said it has called up 300,000 army reservists for its "Swords of Iron" campaign, as Palestinians brace for what many fear will be a ground invasion into the long-blockaded Palestinian enclave.

Shlomo Zorno, one of the reservists, pulls a rifle and a flak vest from the trunk of his vehicle. He is already clad in fatigues.

A resident of Ashkelon, a city close to the Gaza Strip where numerous rockets have fallen, including one "very close" to his house, he says he "didn't think for a second" after being summoned to active duty.

Hamas's assault launched on Saturday has so far killed at least 800 Israelis and injured 2,600 more, while militants forced around 150 hostages back to the Gaza Strip, the Israeli government said.

Israeli retaliatory strikes on Gaza targets have killed 687 people and wounded another 3,727, according to the Hamas-controlled health ministry.

"We knew this kind of assault could happen," said Zorno, 42, a teacher in civilian life.

Ran Singerman, 30, was "on vacation in the north" of Israel when he received the call.

He does not know how long he will serve, he said, but welcomed the chance to defend his country.

Since joining, he has organised logistical support for other soldiers and reservists, "so they can sleep better and do their jobs better".

With sleeping bags and ground mats in his arms, Singerman said his mother Any, aunt and uncle had arranged the supply of equipment.

"All the people help the army of this marvellous country," which must be "united," said Any Gotleyb, 62.

- 'Our 9/11' -

Just days ago, Israel was divided by a judicial reform bill pushed by the hard-right government of Prime Minister Benjamin Netanyahu. The plan sparked mass protests at least weekly, with detractors warning it paves the way for authoritarian rule.

The bill seeks, among other things, to restrict the powers of the Supreme Court in favour of the executive.

Some reservists had threatened not to report for duty in protest, raising national security concerns.

But for now, Israelis appear to have put such divisions aside for the war effort.

Though Eran Levine was wounded during his military service, the 25-year-old still hopes to re-enlist.

"This is our 9/11. Before this happened, you know, we were split," he said at the Ramla base.

"When something like this happens, you've got to... get together and fight a common enemy that's trying to destroy us and kill us," said Levine, who was part of the demonstrations against the reform bill.

"Everything else next to it becomes insignificant," he continued.

"We need to put our differences aside and unite. Because if we're united, nobody can beat us."