Hamas fired dozens of rockets into southern Israel on Thursday, killing three people, and Israel launched numerous air strikes across the Gaza Strip, threatening a wider offensive to halt repeated Palestinian salvos.

Israeli police said the three died when a Palestinian rocket hit a four-story building in the town of Kiryat Malachi, some 25 kilometres north of Gaza. They were the first Israeli fatalities of the latest conflict to hit the coastal region.

“The murderous attack, we saw on Israel this morning is unfortunately another aberration. We’ve seen over the previous months consistent rocket attacks from Gaza into Israel, Hamas and its terrorist allies targeting our civilian population, with rockets, with missiles on an ongoing basis. What we are trying to do now in Gaza is to hit the Hamas military machine in order to safeguard and protect our people. No country would allow the continuous bombardment of its civilians in this manner,” said Israeli government spokesperson Mark Regev.

Israel on Wednesday assassinated Hamas’s military mastermind and shelled the enclave from the land, sea and air, killing 13 people, including five militants, three children and a pregnant woman. More than 100 were wounded.

The UN Security Council held an emergency meeting late on Wednesday to discuss the Israeli assault. It called for a halt to the violence, but took no action.

Expecting days or more of fighting, Israel warned Hamas that all its men were in its sights and dropped leaflets in Gaza telling residents to keep their distance from militants and Hamas facilities.

Israel weathered censure from influential Arab powers Egypt and Qatar. The United States condemned Hamas, shunned by the West as an obstacle to peace for its refusal to renounce violence and recognize Israel.

Hamas has said the killing of its top commander, Ahmed Al-Jaabari, would “open the gates of hell” for Israel. It also appealed to neighbouring Egypt to halt the “barbaric” assault.

Israeli Prime Minister Benjamin Netanyahu, whom opinion polls favour for victory in a Jan. 22 general election, said on Wednesday the Gaza operation could be stepped up.

His cabinet has granted authorization for the mobilization of military reserves if required to press the offensive, dubbed “Pillar of Defence” in English and “Pillar of Cloud” in Hebrew after the Israelites’ divine sign of deliverance in Exodus.

The assault came after a week of surging cross-border violence and defied hopes that Egypt had brokered a truce.

Within hours of a missile destroying Jaabari’s car, militants fired a slew of rockets against the Jewish state’s desert south.

Israel’s military reported that its Iron Dome interceptor had shot down more than 30 of the missiles.

Israel said it had destroyed much of Gaza’s longer-range rocket stockpiles.

Egypt, whose new Islamist-rooted government pledged to honour the 1979 peace treaty with Israel, condemned the new Israeli raids as a threat to regional security. It recalled its ambassador from Israel and called for an emergency session of the UN Security Council.