Palestinian rescue workers search the rubble for survivors following an Israeli military strike on Rafah, in the southern Gaza Strip, on August 1, 2014. A 72-hour ceasefire took effect today in Gaza but was immediately threatened by deadly shelling, as diplomats pressed for a more durable end to 25 days of devastating violence. Photo by Abed Rahim Khatib/Flash90

Palestinian rescue workers search the rubble for survivors following an Israeli military strike on Rafah, in the southern Gaza Strip, on August 1, 2014. A 72-hour ceasefire took effect today in Gaza but was immediately threatened by deadly shelling, as diplomats pressed for a more durable end to 25 days of devastating violence. Photo by Abed Rahim Khatib/Flash90

A Palestinian rescue workers dig out the body of a man from the rubble of his home following an Israeli military strike on Rafah, in the southern Gaza Strip, on August 1, 2014. A 72-hour ceasefire took effect today in Gaza but was immediately threatened by deadly shelling, as diplomats pressed for a more durable end to 25 days of devastating violence. Photo by Abed Rahim Khatib/Flash90

Palestinian rescue workers search the rubble for survivors following an Israeli military strike on Rafah, in the southern Gaza Strip, on August 1, 2014. A 72-hour ceasefire took effect today in Gaza but was immediately threatened by deadly shelling, as diplomats pressed for a more durable end to 25 days of devastating violence. Photo by Abed Rahim Khatib/Flash90

Palestinian rescue workers search the rubble for survivors following an Israeli military strike on Rafah, in the southern Gaza Strip, on August 1, 2014. A 72-hour ceasefire took effect today in Gaza but was immediately threatened by deadly shelling, as diplomats pressed for a more durable end to 25 days of devastating violence. Photo by Abed Rahim Khatib/Flash90

A wounded Palestinian woman arrives at al-Najar hospital in the southern of Gaza strip, on August 1, 2014. A 72-hour ceasefire took effect today in Gaza but was immediately threatened by deadly shelling, as diplomats pressed for a more durable end to 25 days of devastating violence. Photo by Abed Rahim Khatib/Flash90

A wounded Palestinian man arrives at al-Najar hospital in the southern of Gaza strip, on August 1, 2014. A 72-hour ceasefire took effect today in Gaza but was immediately threatened by deadly shelling, as diplomats pressed for a more durable end to 25 days of devastating violence. Photo by Abed Rahim Khatib/Flash90

A Palestinian family flee their homes in Rafah, in the southern Gaza Strip, to a safer location following Israeli military strikes on their neighborhood on August 1, 2014. A 72-hour ceasefire took effect today in Gaza but was immediately threatened by deadly shelling, as diplomats pressed for a more durable end to 25 days of devastating violence. Photo by Abed Rahim Khatib/Flash90

Smoke rises following what witnesses said were Israeli air strikes in Rafah in the southern Gaza Strip on August 1, 2014. A Gaza ceasefire crumbled only hours after it began on Friday, with at least 40 Palestinians killed by Israeli shelling and Israel accusing militants of violating the U.S.- and U.N.-brokered truce by firing rockets and mortars. The 72-hour break announced by U.S. Secretary of State John Kerry and U.N. Secretary-General Ban Ki-moon was the most ambitious attempt so far to end more than three weeks of fighting, and followed mounting international alarm over a rising Palestinian civilian death toll. Photo by Abed Rahim Khatib/Flash90

Smoke rises following what witnesses said were Israeli air strikes in Rafah in the southern Gaza Strip on August 1, 2014. A Gaza ceasefire crumbled only hours after it began on Friday, with at least 40 Palestinians killed by Israeli shelling and Israel accusing militants of violating the U.S.- and U.N.-brokered truce by firing rockets and mortars. The 72-hour break announced by U.S. Secretary of State John Kerry and U.N. Secretary-General Ban Ki-moon was the most ambitious attempt so far to end more than three weeks of fighting, and followed mounting international alarm over a rising Palestinian civilian death toll. Photo by Abed Rahim Khatib/Flash90