Israel’s airstrike on a school in Gaza cannot be justified, top EU diplomat Josep Borrell said on Saturday. The attack by the Israel Defense Forces (IDF) earlier in the day reportedly killed around 100 people.

Borrell said he was “horrified by the images” from the scene. The Tabeen school in central Gaza City was reportedly used to shelter displaced people. Women and children were among the victims, the local authorities said, adding that the death toll could rise since some people have yet to be pulled from the rubble.

According to media estimates, up to 6,000 people may have been sheltering at the school when it was hit by three Israeli missiles. West Jerusalem claimed that it was targeting a “Hamas control center” in the facility. The Gaza-based Palestinian militant group denied having a base at the school.

“At least 10 schools were targeted in the last weeks. There’s no justification for these massacres,” Borrell wrote on X (formerly Twitter). He went on to say that the EU is “dismayed by the terrible overall death toll” in the conflict between Israel and Hamas.

The fighting broke out after Hamas launched a surprise attack on Israel on October 7 last year. The militants killed around 1,100 people in a raid on Israeli settlements near Gaza and took more than 200 people hostage.

West Jerusalem responded with bombing campaign followed by a ground operation in Gaza. The hostilities have claimed the lives of around 39,8000 Palestinians, according to the Gaza Health Ministry. Borrell put the number at 40,000 in his post.

Earlier on Saturday, Moscow condemned the Israeli attack, saying it is “deeply shaken” by the developments. Russia is calling on Israel to “refrain from attacks on civilian targets,” Foreign Ministry spokeswoman Maria Zakharova said, adding that “there is no and can be no justification for such actions.”

Several nations, including Qatar, Egypt, and the US, have sought to mediate a truce between the warring parties. On Thursday, the White House published a joint statement from Washington, Doha, and Cairo calling on both sides to conclude a ceasefire and trade the hostages held by Hamas for Palestinian detainees in Israeli custody.

The proposal was slammed by Israeli Finance Minister Bezalel Smotrich, who called it a “surrender” and a “dangerous trap.” His words sparked outrage in Washington. White House National Security Communications Adviser John Kirby said the administration of President Joe Biden “won’t allow extremists to blow things off course.”

Borrell also criticized Smotrich on Saturday, condemning the finance minister’s opposition to the deal. “A ceasefire is the only way to stop the killing of civilians and secure the hostages’ release,” he said.