JERUSALEM (AP) — Israel’s military ordered a complete siege on the Gaza Strip on Monday, halting deliveries of food, water, fuel and supplies to its 2.3 million people as it pounded the Hamas-ruled territory with waves of airstrikes in retaliation for the militants’ bloody weekend incursion.

More than two days after Hamas launched its surprise attack, the Israeli military said it had largely gained control in its southern towns where it had been battling Hamas gunmen. Israel’s vaunted military and intelligence apparatus was caught completely off guard by Hamas, resulting in heavy battles in its streets for the first time in decades.

Israeli tanks and drones were deployed to guard breaches in the Gaza border fence to prevent new incursions. Thousands of Israelis were evacuated from more than a dozen towns near Gaza, and the military summoned 300,000 reservists — a massive mobilisation in a short time.

The moves, along with Israel’s formal declaration of war on Sunday, pointed to Israel increasingly shifting to the offensive against Hamas, threatening greater destruction in the densely populated, impoverished Gaza Strip.

At press time last night, civilians on both sides have suffered a terrible toll, Around 700 people, including 73 soldiers, have been killed in Israel, and 493 people have been killed in Gaza, according to authorities on each side. Israel says hundreds of Hamas fighters have been killed. Thousands have been wounded on both sides. Hamas and other militants in Gaza say they are holding more than 130 soldiers and civilians snatched from inside Israel.

In response to Israel’s bombardment, spokesman of Hamas’ armed wing, Abu Obeida, said in an audio released Monday night that the group will kill one Israeli civilian captive any time Israel targets civilians in their homes in Gaza “without prior warning. Israeli Foreign Minister Eli Cohen warned Hamas against harming any of the hostages, saying, “This war crime will not be forgiven.”

A major question remains whether Israel will launch a ground assault into the tiny Mediterranean coastal territory, a move that in the past has brought even greater casualties.

Israel and Hamas have had repeated conflicts in past years, often sparked by tensions around a Jerusalem holy site. This time, the context has become potentially more explosive, and both sides talk of shattering with violence a years-long Israeli-Palestinian deadlock left by the moribund peace process.

Israel has been stunned by a surprise attack and death toll unseen since the 1973 war with Egypt and Syria. That is fomenting calls to crush Hamas no matter the cost, rather than continuing to try to bottle it up in Gaza. Israel is run by its most hard-right government ever, dominated by ministers who adamantly reject any Palestinians statehood.

Hamas, in turn, says it is ready for a long battle to end an Israeli occupation it says is no longer tolerable. Desperation has grown among Palestinians, many of whom see nothing to lose under unending Israeli control and increasing settler depredations in the West Bank, the blockade in Gaza and what they see as the world’s apathy.

“I ask you to stand firm because we are going to change the Middle East,” Israeli Prime Minister Benjamin Netanyahu told authorities from the south Monday. “I know you have been through terrible and difficult things. What Hamas will go through will be difficult and terrible…we have only just begun.”

In the early evening, the sound of explosions echoed over Jerusalem when a volley of rockets fired from Gaza hit two neighbourhoods — a sign of Hamas’s reach. Israeli media said seven were wounded.

Monday evening, Israeli warplanes carried out an intense bombardment of Rimal, a residential and commercial district of central Gaza City, after issuing warnings for residents to evacuate. Amid continuous explosions, the building housing the headquarters of the Palestinian Telecommunications Company was destroyed.

Israeli Defense Minister Yoav Gallant ordered a “complete siege” on Gaza, saying authorities would cut electricity and block the entry of food and fuel.