JERUSALEM — Hamas militants in the Gaza Strip used a tunnel to enter Israel and kill two soldiers on Saturday, and another Israeli died in a rocket strike, officials said.
Intensified bombardments in Gaza raised the reported Palestinian death toll to more than 100 since the start of an Israeli ground offensive on Thursday.
On Israel's border with Gaza, a group of heavily armed Hamas militants disguised as Israeli soldiers emerged from a tunnel and fired an antitank missile at a passing army jeep, killing the two soldiers and wounding four others, the army said.
The military said troops returned fire, killing one gunman as the rest of the group retreated to Gaza. The soldiers' deaths brought to five the number of Israelis killed since the start of the Gaza campaign.
Israeli troops operating up to two miles inside Gaza uncovered 13 Hamas tunnels, five of them leading to Israel, military officials said. The stated aim of the ground push is to search for and destroy networks of tunnels built by Hamas, the Islamist militant group that controls Gaza.
But the stepped-up bombardments accompanying the ground incursion, which followed 10 days of airstrikes, have led to a sharp increase in Palestinian deaths and raised concerns about a growing humanitarian crisis in the densely populated territory.
Israel launched its military campaign there on July 8, saying it was acting to quell rocket fire from the enclave by Hamas.
Among those killed in Israeli shelling on Saturday were a couple and their two children, ages 2 and 3, in the town of Beit Hanoun in northern Gaza, Palestinians reported.
Gaza health officials said more than 330 Palestinians have been killed since the start of the Israeli bombardments of Gaza, and about 2,500 have been injured. The United Nations said more than 70 percent of the dead were civilians, including more than 70 children.
The Israeli army said that it had killed 70 militants in skirmishes since the ground operation began.
As the Israeli troops have advanced, tens of thousands of people have fled their homes, and the United Nations Relief and Works Agency, which assists Palestinian refugees, said more than 60,000 Gazans had taken refuge in 49 shelters provided by the agency, most of them schools.
"The speed with which this has happened is staggering," said Robert Turner, director of operations for UNRWA in Gaza. "The number of displaced persons doubled in one day." Turner said that if the stream of arrivals continues, the agency would run out of basic stocks of mattresses and other vital supplies.
U.N. agencies reported that damage to water and electricity lines had caused widespread power outages and left 900,000 people without running water. About half of the sewage pumping and wastewater treatment systems in Gaza were no longer functioning, the agencies said.
Militants in Gaza fired volleys of rockets at Israel on Saturday, killing a man in a Bedouin encampment near Dimona, a town near the site of Israel's nuclear reactor. Four of the man's relatives were wounded, including a 3-month-old baby who was in serious condition.
The Bedouin, part of Israel's Arab minority, live in shantytowns scattered across the southern Negev region, and lack early warning systems and shelters that have prevented casualties in Israeli cities and towns.
U.N. Secretary-General Ban Ki Moon planned to travel to the region to try to end to the fighting. Diplomatic efforts continued Saturday with no signs of progress.
At a news conference in Cairo with French Foreign Minister Laurent Fabius, Egypt's foreign minister, Sameh Shukri, said his country had no plans to revise a cease-fire proposal that has been rejected by Hamas.