Israel continued to pound Gaza from air, land and sea overnight. At least 17 people were killed and more than 200 wounded in the latest Israeli airstrike on a crowded shopping area in the southern city of Khan Yunis.
The most devastating attack occurred earlier in the day when two shells hit the UN school where many Palestinians had taken shelter after fleeing from their homes following Israeli warnings.
At least 20 people were killed and 90 others injured in the incident.
"The shell struck Abu Hussein school in Jabaliya, which was sheltering hundreds of newly-displaced Palestinians," Abu Ali, a local resident.
At least 92 Palestinians were killed and over 260 injured in Israeli attacks today, Gaza officials said.
Three Israeli soldiers were also killed while trying to destroy a booby-trapped tunnel inside the Gaza Strip, raising the military casualty on the Israeli side to 56 since the start of Operation Protective Edge on July 8.
Israeli Army said they had been killed "while uncovering an offensive tunnel shaft in a residence in the southern Gaza Strip”.
In total, 1,323 people in Gaza have been killed and more than 7,350 have been wounded since the conflict between Israel and Hamas began on July 8, Gaza officials said.
The attack on a UN school in Gaza was second in a week. Last week, 16 people were killed and hundreds wounded when another school in northern Gaza was hit.
UN Secretary General Ban Ki-moon condemned as "unjustifiable and shameful" the shelling of the school and said those responsible for the attack should be held accountable.
The UN Chief said "all available evidence" points to Israeli artillery as the cause of the "reprehensible attack".
US also condemned the shelling of the school in Gaza where displaced Palestinians were sheltering from an assault by Israeli forces on Hamas militants.
Israel, which has accused the militant group Hamas of using schools as bases to launch rockets, said it was investigating the reports.
The Israeli military had ‘ruled out’ that it was responsible for the attack, saying a single "errant" shell had landed in an empty courtyard.     

The attack came a day after one of the bloodiest days in the fighting between Israel and Hamas in which more than 100 people were killed.
Israel Defence Forces (IDF) said that it had targeted "75 terror sites" in the Gaza Strip overnight.
The current conflict is now the longest between Israel and militants from Gaza. The longest so far was 22 days in 2008 when Israeli army also entered Gaza "to destroy terrorist infrastructure".
Announcing the four-hour humanitarian pause, IDF Chief of Staff Lieutenant General Benny Gantz said, "The lull will not apply to areas where the Israeli army continues to operate in search of tunnels."
But Hamas said that it had not so far agreed to any new truce.
"When we have an Israeli commitment... on a humanitarian truce, we will look into it," spokesman Sami Abu Zuhri said.
The Israeli security cabinet will meet to discuss an Egyptian proposal for a ceasefire.
Israel stepped up the intensity of its strikes yesterday after a brief pause on Monday, saying that it had hit a number of tunnels dug by militants to infiltrate and attack the country.
Prime Minister Benjamin Netanyahu also warned people to get ready for a prolonged war after rockets continued to land in Israel from Gaza.
International efforts have so far failed to get Israel and Hamas to agree to a truce and start negotiations.
Hamas on Tuesday rejected a fresh ceasefire proposal put forward by the Palestinian Authority that called for a 24-hour truce that could be extended to 72 hours.

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