Twenty-one soldiers were killed and several others injured  in the Gaza Strip in the deadliest attack on Israel’s forces since the October 7 Hamas attacks that triggered the war, the military said Tuesday, a major setback that could add to mounting calls for a cease-fire.

The reservists were preparing explosives to demolish two buildings in central Gaza on Monday when a terrorist fired a rocket-propelled grenade at a tank nearby. The blast triggered the explosives, causing both two-story buildings to collapse on the soldiers inside.

It was unclear to what extent the buildings’ collapse was due to the force of the RPG and how much was caused by the secondary explosions of the mines, but it is now being investigated. According to Israeli press reports, the scene of the destruction resembled the aftermath of an earthquake and rescue activities were under way for several hours.

Prime Minister Netanyahu has vowed to press ahead until Israel crushes the ruling Hamas terrorist group and wins the freedom of the more than 100 hostages held captive in Gaza. Israelis are increasingly divided on the question of whether it is possible to do either, and large numbers of Israeli casualties have pressured Israel’s government to halt past military operations.

“On this difficult and painful morning,” the defense minister, Yoav Gallant, stated on X, “the most tragic news reached many homes in Israel; our hearts are with the dear families in their most difficult time. This is a war that will determine the future of Israel for decades to come — the fall of the fighters is a requirement to achieve the goals of the war.”

The fallen soldiers in Monday’s incident were pressing ahead with those goals, under challenging circumstances. According to the Times of Israel, they were undertaking efforts to destroy Hamas sites as part of a wider effort to establish a buffer zone that can eventually allow the residents of Israeli communities that border Gaza to safely return to their homes. 

Another Israeli minister, Benny Gantz, expressed his “heartfelt condolences to the families of the fallen and wishes of recovery to the wounded,” adding on X, “We must be united, remember the heavy price we are forced to pay for such a just war and the lofty goal for which our heroes fell — to secure our future, to return our daughters and sons, and to take care of Israel forever.”

In the meantime, families of the hostages and many of their supporters have called for Israel to reach a cease-fire deal, saying that time is running out to bring the hostages home alive. On Monday, dozens of hostages’ relatives stormed a Knesset committee meeting, demanding a deal to win their loved ones’ release.

Israel’s offensive in the Gaza Strip pounded the southern city of Khan Younis on Monday, pushing thousands of Palestinians to flee even farther south. Hamas is believed to have suffered heavy losses but has continued to put up stiff resistance in the face of one of the deadliest air and ground offensives in recent history.

Terrorists are battling Israeli forces across the territory and launching rockets into Israel. The attack that killed the soldiers occurred some 600 yards from the border at Maghazi, one of three built-up refugee camps in central Gaza dating back to the 1948 war surrounding Israel’s creation. 

Ground operations have been focused on the camps, as well as the southern city of Khan Younis, after Israel claimed to have largely defeated Hamas in northern Gaza. Israel believes Hamas commanders may be hiding in vast tunnel complexes beneath Khan Younis, the hometown of the group’s top leader in the Gaza Strip, Yehya Sinwar, whose location is unknown. Hamas henchmen are also believed to be using hostages as human shields, further complicating any rescue efforts.