Israel pounded the Gaza enclave with a barrage of missiles for a fifth day on Sunday, killing at least 18 people, including women and children, targeting media houses and the home of a Hamas official, and threatening to "send Gaza back to the Middle Ages".
At least seven members of the same family, including four children, were among nine dead when an Israeli missile hit a home in Gaza City. Three people were killed in air strikes, medics said.
Three children were killed when a refugee camp in central Gaza became the target of Israeli attacks. The attacks also wounded 12 people.
Later in the day, another strike killed three people, including two women, in the narrow Gaza Strip.
At least eight Palestinian journalists were injured when air raids hit buildings housing local media offices on Sunday in strikes that have already claimed over 60 lives.
While the first round of strikes destroyed a building housing Arab Al Quds television network, the second round of raids hit a building with offices of Sky News, al-Arabiya, and the official Hamas-run channel al-Aqsa TV.
One of the injured Palestinian journalists had to have his leg amputated.
Russian TV network Russia Today said its office in one of the buildings was also damaged.
Even as media reports said efforts for a ceasefire were on, Prime Minister Benjamin Netanyahu stated that Israel was ready to "significantly expand" its operation in Gaza.
Israel's Interior Minister Eli Yishai went a step ahead when he said, "The goal of the operation is to send Gaza back to the Middle Ages".
"Only then will Israel be calm for 40 years," Yishai was quoted as saying by Haaretz newspaper.
Meanwhile, fighters in Gaza fired rockets into Israel though two of them, aimed at the commercial hub of Tel Aviv, were shot down by Israel's anti-missile system, reports said.
Huge plumes of smoke were seen across the Gaza sky after five days of incessant bombing, which Israel says is aimed at deterring Hamas fighters from launching rockets into its territory.
The violence escalated after Israel killed a Hamas military commander in a raid on Wednesday.
Fears are also growing of a ground assault by Israel as thousands of Israeli troops backed by armour gathered along the border.
"We are extracting a heavy price from Hamas and the terror organisations. The army is prepared to significantly expand the operation," Netanyahu said at the weekly cabinet meeting.
The Israeli military said its aircraft had targeted dozens of underground rocket launchers overnight, "causing severe damage to the rocket launching capabilities of Hamas and other terror organisations".
It said that its navy had also shelled Gaza.
Egypt, meanwhile, stepped up efforts to achieve a truce as it hosted Palestinian and Israeli officials for ceasefire talks.
French diplomat Fabius termed it "an emergency situation" and pleaded that "war must be avoided".
While United States President Barack Obama declared that he respects Israel's right to defend itself, British Foreign Secretary William Hague warned Israel that a ground assault by it may cost it international support.
Egyptian President Mohammed Mursi also warned that an Israeli ground invasion would have "serious repercussions". He said Egypt would never accept it "and neither will the free world".