GAZA CITY, Gaza Strip — The first major ground battle in two weeks of Israel-Hamas fighting exacted a steep price Sunday: It killed 65 Palestinians and 13 Israeli soldiers and forced thousands of terrified Palestinian civilians to flee their neighborhood, reportedly used to launch rockets at Israel and now devastated by the fighting.

Israeli Prime Minister Benjamin Netanyahu said the offensive would continue “as long as necessary” to end attacks from Gaza on Israeli civilians.

But Hamas seems defiant, international cease-fire efforts are stalled, and international criticism is becoming more vocal as the death toll among Palestinian civilians rises.

U.N. chief Ban Ki-moon called Israel’s latest incursion “atrocious,” and said it must do far more to protect civilians. The U.N. Security Council was holding an emergency session Sunday night at the request of council member Jordan on the situation in Gaza.

In Israel, public opinion will struggle to tolerate rising military losses in an open-ended campaign. Already, Sunday’s deaths marked the highest number of soldiers killed on a single day since Israel’s war in Lebanon in 2006.

The ferocious battle in Gaza City’s Shijaiyah neighborhood came on the third day of Israel’s ground offensive, which had been preceded by a 10-day air campaign.

In all, at least 432 Palestinians were killed and more than 3,000 wounded in the past two weeks. The overall death toll on the Israeli side rose to 20, including 18 soldiers, along with dozens of wounded troops, during that period.

On Sunday evening, Hamas spokesman Mushir al-Masri in Gaza claimed his group had captured an Israeli soldier. An announcement on Gaza TV of the soldier’s capture set off celebration in the streets of Gaza City.

But the claim could not immediately be verified, and the Israeli military said it was investigating the report. “There’s no kidnapped Israeli soldier,” Israel’s ambassador to the U.N., Ron Prosor, told reporters Sunday night.

Hamas has made similar claims of capturing Israelis in the past that were not true. For Israelis, a captured soldier would be a nightmare scenario. Hamas-allied militants seized an Israeli soldier in a cross-border raid in 2006 and held him captive in Gaza until Israel traded more than 1,000 Palestinian prisoners, some of whom were involved in grisly killings, for his return in 2011.

Sunday’s battle began when Israeli troops backed by tanks entered the densely populated Shijaiyah district just after midnight Sunday. They were met by a “huge” level of resistance by Hamas fighters who fired anti-tank missiles, rocket-propelled grenades and automatic weapons from houses and buildings, said Lt. Col. Peter Lerner, an army spokesman.

Residents said they came under intense Israeli tank fire.

“The gate of hell has opened, and shrapnel came through the windows,” Shijaiyah resident Jawad Hassanain said by phone. He and his family fled to a nearby building after their house shook from explosions.

After daybreak, the extent of the devastation slowly became apparent: At least 65 Palestinians had been killed and nearly 300 wounded, Gaza health officials said, while dozens of homes badly damaged or destroyed.

Gaza official says Israeli shells hit hospital

GAZA CITY, Gaza Strip — Israeli tank shells struck a hospital in central Gaza on Monday, a health official and a doctor at the facility said. The health official said the shells killed at least four people and wounded 60, including 30 medical staff.

The Israeli military said it was looking into the report.

Health official Ashraf al-Kidra said 12 shells hit the Al Aqsa hospital in the town of Deir el-Balah. He said the shells landed in the administration building, the intensive care unit and the surgery department.

Live footage on Hamas’ Al Aqsa TV station showed wounded being moved on gurneys into the emergency department.

A doctor at the hospital, Fayez Zidane, told the station that shells hit the third and fourth floor as well as the reception area.

“There is still shelling against the hospital,” he said. He said he found bits of a rocket, presumably from one of the projectiles.

Zidane appealed to the Red Cross and a nearby hospital to send help.

Kerry returns to Mideast to push for cease-fire

WASHINGTON— U.S. Secretary of State John Kerry is making a renewed push for a cease-fire between Israel and Hamas with another trip to the Middle East after the civilian death toll in the conflict sharply escalated over the weekend.

Kerry left Washington early Monday for Cairo, where he will join diplomatic efforts to resume a truce that had been agreed to in November 2012.

He will urge the militant Palestinian group to accept a cease-fire agreement offered by Egypt that would halt nearly two weeks of fighting. More than 500 Palestinians and 20 Israelis have been killed in that time.

The Obama administration, including Kerry, is sharpening its criticism of Hamas for its rocket attacks on Israel and other provocative acts, like tunneling under the border. It is also toning down an earlier rebuke of Israel for attacks on the Gaza Strip that have killed civilians, including children.