Israeli tank shells slammed into a crowded U.N. school sheltering Gazans displaced by fighting on Wednesday, killing 15 and wounding 90 after tearing through the walls of two classrooms, a spokesman for a U.N. aid agency and a health official said.
Israeli airstrikes and shelling also killed 40 Palestinians elsewhere in the coastal territory Wednesday, including multiple members of two families struck in their homes, health officials said.
The Israeli military said mortar shells had been fired from near the school, and that soldiers fired back.
Later Wednesday, the military declared a four-hour humanitarian cease-fire in parts of Gaza beginning at 3:00 p.m., but Hamas spokesman Sami Abu Zuhri said it lacked any "value" because it excluded border areas from where Hamas wanted to evacuate the wounded.
The Israeli military said forces were still working to demolish tunnels in certain areas of the Strip. It said at least two rockets were fired at Israel following its declaration to partially hold fire.
The latest violence further dimmed hopes of a sustainable truce in the fighting, now in its fourth week. The strike at the U.N. school in the Jebaliya refugee camp came on the heels of Israel's heaviest air and artillery assault so far in the conflict.
Israel escalated its campaign on Tuesday, with airstrikes destroying key symbols of Hamas power, including the home of the top Hamas leader. Gaza's only power plant was shut down after shells set its fuel tank on fire.
On Wednesday, Israeli aircraft struck dozens of Gaza sites, including five mosques it said were being used by militants, while several other areas came under tank fire.
In Jebaliya, tank shells hit the U.N. school before dawn, said Adnan Abu Hasna, a spokesman for the U.N. Relief and Works Agency. The agency is sheltering more than 200,000 people displaced by the fighting at dozens of U.N. schools across the coastal strip.
Assad Sabah said he and his five children were huddling under desks in one of the classrooms because of the constant sound of tank fire throughout the night.
"We were scared to death," he said. "After 4:30 a.m., tanks started firing more. Three explosions shook the school."
"One classroom collapsed over the head of the people who were inside," he said.
In one classroom, the front wall was blown out, leaving debris and bloodied clothing. Another strike tore a large round hole in the ceiling of a second-floor classroom. The wall of the lavatories was also damaged.
The Israeli military said it fired back after its soldiers were targeted by mortar rounds launched from the vicinity of the school.
The mortars were fired from a distance of some 200 metres (yards) from the school, said an Israeli military official, speaking on condition of anonymity because he was not authorized to talk to the media.
About two hours after the strike, hundreds of people still crowded the school courtyard, some dazed, others wailing.
Aishe Abu Darabeh, 56, sat on the ground with her relatives.
"Where will we go?" she asked. "Where will we go next? We fled and they (the Israelis) are following us."
Four of the dead were killed just outside the school compound, two in their home nearby and two in the street, after returning from pre-dawn prayers, their relatives said.
The bodies of two members of the al-Najar family, 56-year-old Shaher and his 41-year-old brother, Bassem, were laid out in one of the rooms of their small home, surrounded by wailing relatives. Outside the gate, another relative held on to his crying son, hugging him tight and saying: "I'm here, I'm not going anywhere."
Chris Gunness, another spokesman for the U.N. Palestinian refugee agency, said the international community must step in.
"We appealed incessantly to the political echelons with power to reduce and end the violence. We warned. Our voice was not heard. It is time for others to honour their international law responsibilities to deal with consequences on civilians of their military decisions," he said.
Israeli leaders have said that troops will not leave until all the Hamas tunnels have been demolished. The army said 32 tunnels have so far been located but did not say how many remain. Since Tuesday morning, troops have demolished three more tunnels, a statement said.