Just 24 hours after the boast by the Israeli Prime Minister, Benjamin Netanyahu, that Israel had crippled the long-range missile capabilities of Palestinian militants in Gaza, two Fajr-5 rockets fired by Islamic Jihad landed just south of Israel's densely populated commercial heartland.
There was no damage or injuries, but sirens wailed across Tel Aviv for the first time since Saddam Hussein's Scud attacks in 1991, sending surprised residents hurrying to shelters. Israeli military officials warned Tel Aviv residents to expect "an unquiet night".
Yesterday morning, Palestinian militants drew their first blood in Israel's Operation Defensive Pillar when three Israelis were killed when a rocket hit an apartment building in Kiryat Malachi, 20 miles from Gaza – one of more than 120 rockets fired from Gaza since the conflict erupted on Wednesday with the assassination of the Hamas military chief in an Israeli air strike.
Israel continued its ferocious barrage of attacks on more than 200 targets across the Hamas-controlled enclave and began moving bulldozers and tanks into position on the border for a possible land invasion. At least 15 Palestinians have died in the current wave of violence, with dozens more left injured. Among those killed was Omar, the 11-month-old son of the BBC's Gaza-based picture editor, Jihad Masharawi.
"I hope that Hamas and the other terrorist organisations in Gaza got the message," Mr Netanyahu told reporters in Tel Aviv. "If not, Israel is prepared to take whatever action is necessary to defend our people."
David Cameron spoke to Mr Netanyahu by phone last night to express his concern for the "extremely dangerous situation". However, a Downing Street spokesman said he "made clear that Hamas bears the principal responsibility for crisis" and that the recent spate of rocket attacks on Israel were "completely unacceptable".
Israel began preparations to call up 30,000 reserve soldiers. Defence Minister Ehud Barak said Hamas "would pay a heavy price" for firing rockets towards Tel Aviv. The Israeli attacks left a trail of destruction across Gaza and sent plumes of smoke soaring into the air. A Hamas spokesman, Fawzi Barhoum, said Israel would also be punished "for this open war which they initiated".
There was some respite after noon prayers, when a crowd of several thousand marched from the Al-Omari Mosque in the centre of Gaza City to a cemetery in the Sheikh Radwan neighbourhood, carrying the body of the Hamas leader Ahmed al-Jabari.
Earlier, hundreds attended the funerals of four children killed in Israeli attacks on Wednesday. Then it was back to routine, with militants firing rockets from civilian areas all over Gaza City.
The Egyptian President, Mohammed Morsi, led Arab calls of condemnation and demanded urgent action from the United Nations and the international community. "The Israelis must realise that this aggression is unacceptable and would only lead to instability in the region and would negatively and greatly impact the security of the region," Mr Morsi said.
His office announced that his Prime Minister, Hisham Kandil, would visit Gaza for the first time with other senior officials in a demonstration of solidarity with the embattled Palestinians. Mr Morsi, who recalled his ambassador immediately after hostilities began, may hold the key to mediating a ceasefire if he threatens to cancel the 1979 Camp David peace treaty that Israel regards as a cornerstone of its security policy.
In Kiryat Malachi, the rocket there destroyed a fourth-floor apartment, killing two Israeli men and a woman from different families. Two others were seriously hurt in the building .
Sirens sounded across the south of Israel every few minutes as rockets rained down in a radius of 40 miles from the border with Gaza. More than 20 rockets were fired at Ashkelon, 13 miles north of the enclave, of which at least 17 were destroyed in mid-air by Israel's Iron Dome air anti-missile system.