Israel warns Gazans to leave homes as air strikes continue
Israel has urged thousands of people in east and north Gaza to leave their homes as it continues air strikes.
An Egyptian truce initiative on Tuesday failed to halt rocket attacks on Israel by Hamas militants and other groups.
Israel, which had its first fatality on Tuesday, said senior Hamas militants had died in strikes on Gaza overnight.
Palestinian officials say at least 211 people have died in Israeli raids, including 10 killed overnight and four children who died later on Wednesday.
An Israeli man was killed by a mortar shell fired from Gaza near the northern border with Israel.
Israel launched its Operation Protective Edge on 8 July. Its stated objective is to halt Palestinian rocket attacks on Israel, but the United Nations says the majority of those killed in Gaza have been civilians.
Analysis: Kevin Connolly, BBC Middle East correspondent, Jerusalem
Twenty-four hours on from the first faltering attempts at a ceasefire, the conflict between Israel and Hamas grinds on to a grimly familiar pattern.
Israel says its warnings are to avoid civilian casualties in planned raids but they'll spread further fear, anger and uncertainty in Gaza where civilians will feel there are no real places of safety now.
Israeli Prime Minister Benjamin Netanyahu now faces a dilemma. There are right-wing members of his cabinet demanding a ground offensive and he doesn't want to look weak in domestic politics. But the risks for him are significant. Ground fighting may cause huge numbers of casualties, alienating Israel's allies, and trap him into a long campaign without a clear exit strategy.
Instinctively he seems to feel that Israelis would prefer to see Hamas diminished and the rocket fire ended through the air campaign. Ground fighting would mean Israeli casualties too.
But if air power doesn't prove decisive, the political pressure for him to go further will grow.
The Israel Defense Forces (IDF) dropped leaflets and used recorded telephone messages to warn some 100,000 residents of Gaza to leave their homes before 08:00 (05:00 GMT) on Wednesday.
The warning came as militants continued to fire rockets at Israeli cities, the IDF said, adding that its Iron Dome missile shield had intercepted 10, including four launched at Tel Aviv.
The military said militants had fired more than 150 rockets into Israel on Tuesday, and more than 1,260 since Operation Protective Edge began.
The air force and navy had carried out strikes on 96 targets in Gaza on Tuesday, and more than 1,750 in the past eight days, it added.
Israeli Prime Minister Benjamin Netanyahu said Hamas had "shut the door to a diplomatic solution" and bore "sole responsibility for the continuation of the violence".
The Egyptian-backed truce was to have started on Tuesday morning, after it was approved by Israel's security cabinet.
The ceasefire should have been followed by a series of meetings in Cairo with high-level delegations from the two sides.
Israeli attacks were halted for six hours, but resumed amid continuing rocket fire directed at Israel. Among those reported killed overnight was a five-month-old baby.
Later on Wednesday, Palestinian medics said four children had been killed in an air raid west of Gaza City.
Hamas - which is designated a terrorist organisation by Israel and the US among others- said the terms of the ceasefire did not address concerns over the economic blockade of the Gaza strip, which has caused severe economic hardship for many Palestinians.
Senior Hamas spokesman Osama Hamdan told the BBC the group had only heard about the truce initiative through the media, and that a ceasefire could not be put in place without the details of any agreement being known.
The armed wing of Hamas, the Izz al-Din Qassam Brigades, dismissed the initiative, saying its battle with Israel would "increase in ferocity and intensity".
Mr Netanyahu has come under criticism in Israel for accepting the truce initiative. His office announced that deputy defence minister Danny Danon had been sacked for comments branding the PM a "failure".
Israel has mobilised tens of thousands of troops on the border with Gaza amid speculation a ground invasion could be launched.
The UN says at least 1,370 homes have been destroyed in Gaza and more than 18,000 people displaced in recent hostilities.
The International Red Cross warned that repeated bombing was devastating Gaza's "fragile water infrastructure", with hundreds of people left without water.
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