GAZA/JERUSALEM - The United States, alarmed by escalating civilian bloodshed in an Israeli offensive in the Gaza Strip, took a direct role in efforts to secure a ceasefire on Monday, as the Palestinian death toll jumped to more than 500.
Despite growing calls for a halt to two weeks of fighting, violence raged on. Israel pounded the coastal strip, killing 28 members of a family in one strike, 11 people in an attack on a high-rise building and four in the shelling of a hospital, medics said.
Israel's losses also mounted. Following the death of 13 soldiers on Sunday, Israel said seven more troops had been killed on Monday, including four whose jeep was fired at by a group of militants who tunnelled across the border from Gaza.
Israeli aircraft hit back swiftly, killing 10 of the infiltrators from the Islamist group Hamas, the army said.
Violence also spread to the occupied West Bank where Palestinian medics said Israeli soldiers shot and killed a Palestinian man, 21, while dispersing protesters throwing stones at a military jeep near Jerusalem.
The Israeli military said it was investigating the incident.
US Secretary of State John Kerry arrived in Cairo to try to secure an end to hostilities, a day after he was caught by an open microphone saying sarcastically that the Israeli assault was "a hell of a pinpoint operation".
Speaking in Washington, President Barack Obama said he was increasingly worried by the conflict. "We have serious concerns about the rising number of Palestinian civilian deaths and the loss of Israeli lives, and that is why it now has to be our focus and the focus of the international community to bring about a ceasefire," he told reporters at the White House.
Hamas, which killed 13 Israeli soldiers in Gaza on Sunday, said it would not lay down its arms until a series of demands were met - including an end to a blockade imposed on the territory by both Israel and Egypt. "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.
At Al-Aqsa hospital in the central Gaza Strip, four people were killed and 70 wounded when an Israeli tank shell slammed into the third floor, which housed operating theatres and an intensive care unit, the Health Ministry said.
The Israeli military, which has accused Hamas militants of firing rockets from the grounds of Gaza hospitals and seeking refuge there, had no immediate comment.
The International Committee of the Red Cross issued a statement condemning the shelling of the hospital "in the strongest terms". It said the hospital came under direct fire at least four times and life-saving equipment had been severely damaged.
Nonstop attacks lifted the Palestinian death toll to 536, including almost 100 children, since fighting started on July 8, Gaza health officials said. Israel says 25 of its soldiers have been killed along with two civilians.