The White House expressed "deep concern" over reports of significant civilian casualties in Gaza as a result of Israel's bombing of a school in Gaza City that killed at least 100 people, including women and children, saying the strike "underscores the need for a ceasefire" without condemning the massacre, or describing it as such.

“We are deeply concerned by reports of civilian casualties in Gaza following an IDF strike on a school compound,” National Security Council spokesman Sean Savitt wrote in a statement released to the press.

"We are in contact with our Israeli counterparts, who said they targeted senior Hamas officials, and we are asking for more details."

"This underscores the need for a ceasefire and hostage agreement, which we continue to work tirelessly to achieve," Savit added.

"I say again that far too many civilians have been killed in Gaza," Vice President Kamala Harris, the Democratic Party's nominee, said Saturday. "Israel has the right to go after Hamas terrorists, but as I have said many times, I believe it has a significant responsibility to avoid civilian casualties."

A group of young pro-Palestinian activists, who boycotted US presidential candidate Kamala Harris earlier this week over concerns that she would not seek meaningful policy changes toward Israel if she won the White House, have launched a campaign to disrupt her campaign rallies across the country.

As is its custom after every massacre it commits, Israel claimed that the school was a Hamas command center and that the strike killed senior Hamas and Islamic Jihad activists.

"Based on Israeli intelligence, approximately 100 Palestinians were killed in the attack; 20 Hamas and Islamic Jihad militants, including senior commanders, were operating from the compound that was hit at the Al-Taban School, using it to carry out terror attacks," said Nadav Shoshani, an Israeli military spokesman.

Savitt added that the United States recognizes that Hamas has used schools in the past, but Israel still must work to minimize harm to civilians.

“We know that Hamas has been using schools as gathering sites and operating from them, but we have also said repeatedly that Israel must take measures to minimize harm to civilians,” he wrote.

According to a statement provided by the Gaza Civil Defense Forces to The Washington Post, at least 11 women and children were among those killed in the Israeli strike on the school.

Three rockets hit the school and the mosque in the early hours of Saturday, a spokesman for the civil defense forces operating under the Hamas-run government told The Associated Press.

There were about 6,000 displaced people in the school seeking shelter.

Israel struck the school days after it agreed to a call by the United States, Egypt and Qatar for Israel and Hamas to continue negotiations to secure a ceasefire and the release of the hostages, with the United States insisting a deal is "closer" than ever.

"There is a good proposal before both sides, and they need to accept that proposal so we can implement it," White House National Security Council spokesman John Kirby told reporters. "We are closer than we think we have been before."

Egypt and Qatar, the other two mediators, also condemned the Israeli strike, with Egypt saying the strike was "clear evidence of the Israeli side's lack of political will to end this brutal war."

The Egyptian Foreign Ministry said in a statement, "The Arab Republic of Egypt condemns in the strongest terms the Israeli bombing of the Al-Tabyeen School, which was sheltering displaced persons in the Al-Daraj neighborhood east of Gaza City, which resulted in the killing of more than 100 Palestinian citizens and the injury of dozens."

The ministry continued, "Egypt considers the continued commission of these large-scale crimes, and the deliberate killing of such large numbers of defenceless civilians whenever mediators intensify their efforts to reach a ceasefire in the Gaza Strip, clear evidence of the Israeli side's lack of political will to end this brutal war."

Qatar described the strike as a "horrific massacre" and a "flagrant violation of the basic principles of international humanitarian law."

Qatar reiterated its call for an urgent international investigation by sending independent UN investigators to investigate the continued targeting of schools and shelters for the displaced by the Israeli occupation forces.