Israeli forces clashed with Hamas militants across the Gaza Strip on Saturday, the Israeli military said, deepening its engagement in the decimated enclave even as the Palestinian death toll from relentless airstrikes in 12 weeks of war soared higher.

The Gaza Health Ministry reported Saturday that 165 people had been killed in Israeli airstrikes and artillery attacks in the previous 24 hours, adding to the ministry’s toll of more than 21,500 people killed in Gaza since the war began with the Oct. 7 Hamas-led raids into Israel.

The Israeli military said late Friday that it had destroyed a Gaza City apartment of the person it considers the mastermind of those attacks, Yahya Sinwar, the Hamas leader who sits atop the Israel military’s most-wanted list in Gaza.

The army said Mr. Sinwar used the apartment as a hide-out and that it destroyed a tunnel shaft discovered by its troops in the apartment’s basement floor, as well as an underground headquarters that served as a nerve center for senior officials from Hamas’s military and political wings.

He was not believed to be in the complex when it was hit, having decamped to the south when the Israeli campaign began.

As global outrage and impatience grows with the war’s devastating human toll, the Biden administration said late Friday that it was bypassing Congress for the second time since the war started for a weapons sale to Israel.