Israel steps up Gaza offensive A Palestinian firefighter tries to extinguish a fire after an Israeli air strike on the Hamas ministry of interior in Gaza City. Photograph: Mohammed Salem/Reuters Israeli war planes pounded Gaza with around 150 air strikes overnight, causing massive explosions in the main cities and sending plumes of black smoke into the sky. The Israeli Defence Forces said it had targeted rocket-launching sites and arms depots, "causing severe damage to terror infrastructures." In a sign that Israel is preparing to further escalate Operation Pillar of Defence, the military said it was calling up 30,000 reservists. The prime minister. Binyamin Netanyahu, has said a ground invasion of Gaza cannot be ruled out. Israel has said it is prepared to suspend its military offensive during the three-hour visit to Gaza of an Egyptian delegation, including the prime minister, Hesham Kandil, if militant groups also cease rocket fire. The visit is aimed at showing solidarity with the Palestinian people, Egyptian officials said. On Thursday evening, two rockets from Gaza crashed near Tel Aviv in the first such attack on Israel's commercial capital in 20 years. One fell into the Mediterranean Sea and the other in an uninhabited part of a suburb south of the city. Two days of Israeli air strikes have killed 19 Palestinians, including seven militants and 12 civilians, among them six children and a pregnant woman. A Hamas rocket killed three Israelis in the town of Kiryat Malachi on Thursday morning. The latest upsurge in the long-running conflict came on Wednesday when Israel killed Hamas's military mastermind, Ahmed al-Jabari, in a precision air strike on his car. Israel then began shelling the coastal enclave from land, air and sea. Israel says its offensive was in response to increasing missile salvoes from Gaza. The bombing has not yet reached the saturation level seen before it last invaded Gaza in 2008, but Israeli officials have said a ground assault remains possible. Air raid sirens sent residents running for shelter in Tel Aviv, a Mediterranean city that has not been hit by a rocket since the 1991 Gulf war, when it was targeted by Saddam Hussein's Iraq. The Tel Aviv metropolitan area is home to more than 3 million people - more than 40% of Israel's population. "This escalation will exact a price that the other side will have to pay," the Israeli defence minister, Ehud Barak, said in a television broadcast shortly after the strike. But an Israeli cabinet statement on Wednesday spoke only of "improving" national security. Speaking at the same time in Gaza, the Hamas leader, Ismail Haniyeh, urged Egypt to do more to help the Palestinians. "We call upon the brothers in Egypt to take the measures that will deter this enemy," the Hamas prime minister said. The resurgent conflict will be the biggest test yet of the commitment of the Egyptian prime minister, Mohamed Mursi, to Egypt's 1979 peace treaty with Israel, which the west views as the bedrock of Middle East peace. Cairo recalled its ambassador from Israel on Wednesday. Israel's ambassador left Cairo on what was called a routine home visit, but Israel said its embassy would remain open. The Muslim Brotherhood, which brought Mursi to power in an election after the downfall of Hosni Mubarak, has called for a "day of rage" in Arab capitals on Friday. The Brotherhood is seen as the spiritual mentor of Hamas. Israeli war planes have dropped leaflets in Gaza advising residents to stay away from Hamas and other militants. UN diplomats said the secretary-general, Ban Ki-moon, would head to Israel and Egypt next week to try to mediate a ceasefire, although they gave no further details.