At least 15 Palestinians were killed during an Israeli military strike near a crowded market in Shejaia on Wednesday, Gaza health ministry spokesman Ashraf al-Qidra said. He said 160 people were also wounded.
The news came after Israel announced a brief, four-hour cease-fire which began at 1200 GMT (3:00 p.m. local time) and appeared not to last. The Israeli military added that areas where troops were "currently operating" would be exempt.
Hamas denounced the pause as having "no value" and continued to fire rockets, saying it would fight on its own terms, not Israel’s, CNN reported from the scene.
According to the Israeli Defense Force, Hamas fired 26 rockets at Israel, two of which were intercepted above Ashkelon and Netivot. IDF said since midnight 84 rockets had been fired at Israel.
Witnesses reported seeing black smoke billowing above the Shejaia neighborhood after intense shelling. Video footage broadcast by Hamas broadcast outlet Al Aqsa showed dead bodies in pools of blood and wounded people being evacuated by residents.
A Palestinian journalist was reportedly among the dead.
An Israeli military spokeswoman said she was checking the report.
UN school struck
Separately, a United Nations-run school in Gaza was shelled Wednesday.
The attack, which killed at least 15 and wounded more than 100 people, happened about 5:30 a.m. (0230 GMT) at the Jebaliya refugee camp in northern Gaza.
Several hours later, it remained a chaotic scene. Shelling had caved in a wall of the classroom harboring most of the victims. Blankets remained on the floor, along with traces of flesh and blood. In the courtyard, benches and chairs were scattered. So were the carcasses of several cows and donkeys killed in the attack.
A Palestinian girl carries belongings as she and her family leave the Abu Hussein U.N. school in the Jebaliya refugee camp, northern Gaza Strip, hit by an Israeli strike earlier, July 30, 2014.
People milled about in shock. Some questioned the rationale for seeking shelter away from home, after heeding Israeli warnings — by phone and leaflet — of pending airstrikes in their respective neighborhoods. If they aren’t safe at a U.N.-run school shelter, several said with resignation, they might as well go home to die.
United Nations Deputy Secretary-General Jan Eliasson was emotional as he spoke about the attack which also injured more than 100 people, saying all indicators show Israeli artillery hit the school, killing at least 16 people who were sheltering there, including children.
The school is one of 85 sites where the U.N. agency for Palestinian refugees said more than 200,000 people are now seeking shelter. This site was so overcrowded that families had set up camp outside, using desks and chairs to define spaces. Daytime temperatures of at least 32 degrees Celsius, or 91 Fahrenheit, only added to the misery.
The United States condemned Israel's shelling of the school in some of the sharpest criticism Washington has leveled at Israel over the more than three weeks of fighting.
White House spokeswoman Bernadette Meehan said the U.S. is also "extremely concerned" that thousands of Palestinians aren't safe in U.N.-designated shelters in Gaza even though Israel's military has told them to evacuate their homes.
Meehan said the U.S. also condemns those responsible for hiding weapons in U.N. facilities in Gaza, adding that the escalation shows the need for a cease-fire as soon as possible.
Some Palestinians believe the outside world has abandoned them. Several people at the school expressed anger toward the international community and Arab leaders whom they say have provided little if any assistance.
The United States has pledged $47 million in humanitarian aid, including an initial $15 million to the UN Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) in response to its recent urgent appeal. Other groups, such as the International Federation of Red Cross and Red Crescent Societies, are delivering aid.
Early morning shelling
Overnight into Wednesday morning, Israel continued to bombard Gaza City with dozens of airstrikes and heavy tank shelling as the conflict between the Jewish state and Hamas entered its 23rd day.
At least 32 Palestinians in the Gaza Strip were killed early Wednesday as the Jewish state said it targeted Islamist militants at dozens of sites across the coastal enclave, health ministry spokesman Ashraf al-Kidra said.
Among the dead were a medic and an infant. An Israeli army spokeswoman said she was checking for details.
Eight people, including five members of the same family in Jebalya, were killed in other strikes, Gaza officials said.
Hospital officials put the total number of Palestinians killed in the conflict to at least 1,224, most of them civilians. On the Israeli side, 53 soldiers and three civilians have been killed since the Jewish state began its offensive July 8 to halt rocket salvoes fired by Gaza's dominant Hamas Islamists and their allies.
The Israeli security cabinet was to convene again Wednesday to assess the situation and consider future steps.
The army said it needed about a week to complete its main mission of destroying cross-border infiltration tunnels and there has been strong Israeli public support for holding course.
Israeli's military issued a statement saying it so far had hit 4,100 targets in Gaza, with a third of them involving Hamas militants' ability to attack Israel with rockets, the Associated Press reported Wednesday.
Despite the soaring death toll, the militants will not cease fire until their demands are met, according to Hamas' military leader, Mohammed Deif.
But Israel's Channel Two TV said progress was being made toward a deal in Cairo, where a Palestinian delegation was expected to arrive for discussions.
The West Bank-headquartered Palestine Liberation Organization, which has been at odds with Hamas for years, said it had garnered the Islamist movement's support for a 24-hour truce, but did not say when that was due to start.
Palestinian President Mahmoud Abbas "was in touch with [Hamas chief Khaled] Meshaal Tuesday and Wednesday. He proposed the 24-hour truce, Meshaal and Hamas agreed," senior Palestinian official Nabil Shaath told AFP on Tuesday.
However, Hamas said so far it had not agreed to any new truce.
"When we have an Israeli commitment ... on a humanitarian truce, we will look into it but we will never declare a truce from our side while the occupation keeps killing our children," Hamas spokesman Sami Abu Zuhri said.
Israel's government had no comment on the proposal.
UNRWA, the main U.N. relief agency in Gaza, said it was at “breaking point” with more than 200,000 Palestinians sheltering in its schools and buildings following calls by Israel for civilians to evacuate whole neighborhoods before military operations.
The agency acknowledged that it had found a cache of rockets in one school but blamed no particular party. Instead, its spokesman, Chris Gunness, condemned "the group or groups who endangered civilians by placing these munitions in our school."
"This is yet another flagrant violation of the neutrality of our premises," Gunness said in a statement. "We call on all the warring parties to respect the inviolability of U.N. property.”
The Israeli assault intensified after the deaths of 10 soldiers in Palestinian cross-border attacks on Monday. Prime Minister Benjamin Netanyahu warned of a long conflict ahead.
Some information for this report was provided by Reuters, AP and AFP. VOA correspondent Scott Bobb contributed reporting from Gaza City. VOA correspondent Margaret Besheer reported from the United Nations.