The armed wing of the Palestinian militant group Hamas has warned that it will kill an Israeli hostage every time Israel's military bombs civilian targets in the Gaza Strip without warning.
Israel has vowed a "complete siege" on the densely populated area in response to a deadly attack on Israel by Hamas fighters on Saturday morning.
Hundreds of people were taken hostage in Israel and transported to Gaza, where they remain captive.
The State Department has said some Americans are among the missing, though it was not clear whether the missing had been taken hostage, were killed or were in hiding.
Abu Obeida, the spokesman of the Qassam Brigades, said in an audio released Monday night that the threat was a response to intense air strikes by Israel on civilian areas.
“We have decided to put an end to this and as of now, we declare that any targeting of our people in their homes without prior warning will be regrettably faced with the execution of one the hostages of civilians we are holding,” he said.
In a video statement Monday, Israel’s foreign minister warned Hamas against harming any of the hostages who were taken from Israel and being held in Gaza. Eli Cohen said Israel was committed to bringing the hostages home “in the spirit of mutual responsibility.”
“We demand Hamas not to harm any of the hostages, Cohen said. “This war crime will not be forgiven,” he added.
Around 1,400 Israelis and Palestinians are dead two days after Hamas launched an attack that caught Israel's vaunted military and intelligence apparatus completely off guard and led to fierce battles in its streets for the first time in decades.
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The Israeli military said it had largely gained control in its southern towns where it had been battling Hamas gunmen. But Hamas and other militants in Gaza say they are holding more than 130 soldiers and civilians snatched from inside Israel.
Photos: Israel-Hamas War
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 mobilization 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.
Already, civilians on both sides have suffered a terrible toll: around 900 people, including 73 soldiers, have been killed in Israel, and 493 people have been killed in Gaza, according to media and authorities on each side. Israel says hundreds of Hamas fighters have been killed. Thousands have been wounded on both sides.