An Israeli mobile artillery unit fires towards the Gaza Strip.

Palestinians mourn the death of their relatives, whom medics said were killed in Israeli shelling, at a hospital morgue in Rafah in the southern Gaza Strip July 21. Israeli tanks shelled militant targets in the Gaza Strip on Monday and a woman died in an air strike after the bloodiest day of a nearly two-week military offensive that showed no signs of abating, despite global calls for a truce.

A Palestinian woman walks past the rubble of a residential building, which police said was destroyed in an Israeli air strike, in Gaza City Tuesday. Israel kept up its assaults in the Gaza Strip on Tuesday, killing three Palestinians in as many air strikes, as U.S. Secretary of State John Kerry arrived in the region with a mission to seek a ceasefire in the 14-day-old conflict

Palestinians evacuate a building after what witnesses said were warning Israeli air strikes next to their homes in Gaza City. Israel kept up its assaults in the Gaza Strip on Tuesday, killing three Palestinians in as many air strikes, as U.S. Secretary of State John Kerry arrived in the region with a mission to seek a ceasefire in the 14-day-old conflict

An Israeli soldier lifts a shell at a site where mobile artillery units are deployed, outside the Gaza Strip.

Israeli tanks stand outside the northern Gaza Strip July 21. The Palestinian death toll in an Israeli offensive in the Gaza Strip jumped to more than 500 on Monday.

Palestinian medics tend to a boy who they said was wounded in an Israeli shelling, at a hospital, in Rafah in the southern Gaza Strip.

Israelis hold flags during a protest in Tel Aviv, in support of Israel's offensive in the Gaza Strip.

Israeli police officers detain a protester suspected of throwing stones during a protest by Israeli Arabs in the northern city of Nazareth, against Israel's offensive in the Gaza Strip. Following the death of 13 soldiers on Sunday, Israel said seven more troops had died on Monday, including four killed when a group of militants tunneled across the border from Gaza and fired at their jeep.

Israelis take cover as a siren warning of incoming rockets sounds in the southern city of Ashkelon July 21. The Palestinian death toll in an Israeli offensive in the Gaza Strip jumped to more than 500 on Monday, as the United States, alarmed by escalating civilian bloodshed, took a direct role in efforts to secure a ceasefire.

Palestinians sleep at a United Nations school, where people who fled heavy Israeli shelling in the Shejaia neighborhood sought refuge during fighting, in Gaza City July 21. Israeli forces killed at least 10 Palestinian militants on Monday after they crossed the border from Gaza through two tunnels, the military said, as the death toll from the two-week conflict passed 500.

Smoke rises after an Israeli missile strike hit Gaza City on Monday. On Sunday, the first major ground battle in two weeks of Israel-Hamas fighting exacted a steep price, killing scores of Palestinians and over a dozen Israeli soldiers and forcing thousands of terrified Palestinian civilians to flee their devastated Shijaiyah neighborhood, which Israel says is a major source for rocket fire against its civilians.

Palestinian rescuers search for bodies and survivors in the rubble of homes that were destroyed by an Israeli missile strike, in Gaza City on Monday.