Israel pounded targets across the Gaza Strip on Tuesday, dashing hopes of a pause in the fighting, as the military said one of its soldiers was missing, presumed dead, following clashes with Hamas Islamists.
International efforts to end the 15-day conflict gathered pace, with U.S. Secretary of State John Kerry holding talks in Egypt and U.N. Secretary General Ban Ki-moon due to arrive in Israel later in the day.
However, there was no sign of any let-up in the fighting around Gaza, with plumes of black smoke spiraling into the sky, and Israeli shells raining down on the coastal enclave.
Hamas and its allies fired a barrage of rockets into southern and central Israel, triggering sirens in Tel Aviv, with one missile striking a nearby town, lightly injuring two people, officials said.
Israel launched its offensive on July 8 to halt missile fire out of Gaza by Hamas, which was angered by a crackdown on its supporters in the occupied West Bank and suffering economic hardship because of an Israeli-Egyptian blockade.
The Israeli military said it had identified the remains of six soldiers killed in an attack on their armored vehicle inside Gaza on Sunday. It had already announced that seven died in the strike and said it was trying to identify the seventh.
Sparking widespread celebrations in Gaza, Hamas's armed wing announced on Sunday that it had captured a soldier in Sunday's clashes. It displayed a photo ID and army serial number of the man, but did not show any image of him in their hands.
The Israeli military believes it was impossible for anyone to have survived the hit on the army APC.
Israel has agreed to mass releases of Palestinian prisoners in the past to secure the freedom of captured soldiers, or even for the return of the bodies of its citizens.
With the conflict entering its third week, the Palestinian death toll rose to almost 550, including nearly 100 children and many other civilians, Gaza health officials said.
The Israeli military said it had killed 183 militants.
Israel's casualties also mounted, with the military announcing the deaths of two more soldiers, bringing the number of army fatalities to 27 - almost three times as many as were killed in the last ground invasion of Gaza in a 2008-2009 war.
Two Israeli civilians have also been killed by Palestinian rocket fire into Israel.
Palestinian militants in Gaza said they had agreed to a five-hour ceasefire on Tuesday to allow Gazan residents to leave their homes and seek vital supplies, and accused Israel of rejecting the proposal. Israeli officials did not comment.
Violence spread to the nearby West Bank, where medics said soldiers shot dead a Palestinian man while dispersing stone-throwing protesters. A Palestinian shot and seriously wounded an Israeli in the Nablus area on Tuesday.
Dispatched by U.S. President Barack Obama to the Middle East to seek a ceasefire, Kerry held talks on Tuesday in Cairo with Egyptian Foreign Minister Sameh Shukri.
Egypt was key to securing an end to a previous bout of Gaza fighting in 2012, but the country's new leadership is openly hostile to Hamas, potentially complicating the negotiations.
"We hope (Kerry's) visit will result in a ceasefire that provides the necessary security for the Palestinian people and that we can commence to address the medium and long-term issues related to Gaza," Shukri said.
Israel has signaled it is not in a hurry to achieve a truce before reaching its goal of crippling Hamas's militant infrastructure, including rocket arsenals and networks of tunnels threatening Israelis living along the Gaza frontier.
Hamas has also said it will not cease hostilities until its demands are met, including that Israel and Egypt lift their blockade of Gaza and its 1.8 million people, and that Israel release several hundred Palestinians detained during a search last month for three Jewish teenagers later found dead.
Israel blamed the killings on Hamas. "The world must understand that Gaza has decided to end the blockade by its blood and its heroism," deputy Hamas leader Ismail Haniyeh said in a televised address on Monday.
Kerry said the United States would provide $47 million in humanitarian aid for Gaza. Washington is "deeply concerned about the consequences of Israel's appropriate and legitimate effort to defend itself," Kerry said. "No country can stand by when rockets are attacking it."
"But always, in any kind of conflict, there is a concern about civilians - about children, women, communities that are caught in it," Kerry said.
Kerry plans to stay in Cairo until Wednesday morning but has no set departure date from the region. Officials said he might travel to Qatar, a Gulf state which has relatively close ties to Hamas and hosts its leader, Khaled Meshaal.
With Israeli shells and bombs hitting Gaza day and night, thousands of people have fled districts close to the border, where the worst of the fighting has taken place. But with access to Israel and Egypt closed, there are few safe havens.
The main U.N. agency in Gaza, UNWRA, said 101,684 people have taken shelter in 69 of its schools, the number of displaced increasing five times in the last five days.
"This crisis of human displacement is a result of the dramatic intensification of Israel's ground offensive," said UNWRA spokesman Chris Gunness.