KIRYAT MALACHI, Israel — Israel and Hamas widened their deadly conflict over Gaza on Thursday, as militants fired dozens of rockets — including one that killed three civilians in an apartment block in this small southern Israeli town — and two longer-range rockets aimed at Tel Aviv, causing no harm but triggering the first air raid warning there set off by incoming fire from Gaza. The death toll in Gaza from Israeli airstrikes rose to at least 16, including four children and a pregnant teenager.
There was no sign that either side was prepared to dial back the confrontation that has threatened a new war in the Middle East, despite entreaties for restraint by world leaders including President Barack Obama and Ban Ki-moon, the U.N. secretary-general, who planned a visit there in coming days. If anything, the Israelis intensified their attacks on Gaza after the Tel Aviv scare and made new moves toward a possible ground invasion.
The Israeli deaths were the first since Israel’s military launched ferocious aerial assaults Wednesday to stop the chronic rocket fire from Gaza, the Palestinian coastal enclave controlled by Hamas, the militant Palestinian group.
The Israel Defense Forces said in a cryptic statement that one of the two longer-range rockets aimed at Tel Aviv landed but did not hit the ground — meaning that it must have crashed into the Mediterranean Sea — and that the other appeared to have landed far outside the city. Exact locations were not specified.
But the Tel Aviv air raid warnings — which residents of Israel’s largest metropolis had not heard except for drills or malfunctions since Saddam Hussein’s Scuds threatened them in the first Persian Gulf War, more than two decades ago — were a reminder of their vulnerability to an attack from Gaza, less than 40 miles away. They also underscored Israel’s stated reason for seeking to destroy the missile-launching sites in Gaza.
Ehud Barak, the minister of defense, said the targeting of Tel Aviv and the scope of the Palestinian rocket fire ‘‘represents an escalation, and there will be a price for that escalation that the other side will have to pay.’’
Barak also dropped a further hint that planning for a ground invasion of Gaza had begun, saying he had instructed the army to broaden its draft of reservists to ‘‘be prepared for any kind of development if and when it will be required.’’
Israeli officials said 30,000 reservists could be called, and heavy machinery and tanks rumbled south along Israeli roads leading to Gaza on Thursday in preparation for a possible invasion.
The Israel Defense Forces said that within hours of the Tel Aviv air raid warning, they had attacked 70 underground rocket-launching sites in Gaza, and ‘‘direct hits were confirmed.’’ There were also unconfirmed reports that Israeli rockets had struck near Gaza’s Rafah crossing into Egypt, forcing the Egyptians to close it.
Brig. Gen. Yoav Mordechai, a spokesman for the Israel Defense Forces, said its aerial assaults had hit more than 200 sites in Gaza by late Thursday, and ‘‘we'll continue tonight and tomorrow.’’ He also said militants in Gaza had fired about 300 rockets into southern Israel and at least 100 more had been intercepted by Israel’s Iron Dome antimissile defense system.
The Israeli aerial assault on Gaza that began Wednesday was the most intense military operation by Israel in Gaza since an invasion four years ago.
The regional perils of the situation sharpened as President Mohammed Morsi of Egypt warned that his country stood by the Palestinians against what he termed Israeli aggression, echoing similar condemnation Wednesday.
‘'The Egyptian people, the Egyptian leadership, the Egyptian government, and all of Egypt is standing with all its resources to stop this assault, to prevent the killing and the bloodshed of Palestinians,’’ Morsi said in nationally televised remarks before a crisis meeting of senior ministers.
He also instructed his prime minister to lead a delegation to Gaza on Friday and said he had contacted Obama to discuss strategies to ‘‘stop these acts and doings and the bloodshed and aggression.’’
In language that reflected the upheaval in the political dynamics of the Middle East since the overthrow of Hosni Mubarak last year, Morsi said: ‘‘Israelis must realize that we don’t accept this aggression and it could only lead to instability in the region and has a major negative impact on stability and security in the region.’’
The thrust of Morsi’s words seemed confined to diplomatic maneuvers, including calls to Ban, the U.N. secretary-general; the head of the Arab League; and Obama.
An Israeli official confirmed that Ban would be coming to the region Tuesday and holding meetings in Jerusalem, Cairo and Ramallah, the headquarters of the Palestinian Authority in the West Bank. He is not expected to go to Gaza and it was not immediately clear whether he would be coming with a plan.
The 120-nation Nonaligned Movement, the biggest bloc at the United Nations, added its condemnation of the Gaza airstrikes in a statement released by Iran, which holds the group’s rotating presidency and is one of Israel’s most ardent foes.
''Israel, the occupying power, is, once more, escalating its military campaign against the Palestinian people, particularly in the Gaza Strip,’’ the group’s coordinating bureau said in the statement. The group made no mention of the Palestinian rocket fire but condemned ‘‘this act of aggression by the Israelis and their resort to force against the defenseless people’’ and demanded ‘‘decisive action by the U.N. Security Council.’’
In his conversation with Obama, Morsi said, he ‘‘clarified Egypt’s role and Egypt’s position; our care for the relations with the United States of America and the world; and at the same time our complete rejection of this assault and our rejection of these actions, of the bloodshed, and of the siege on Palestinians and their suffering.’’
In Washington, Obama administration officials said they had asked Egypt to use its influence with Hamas to help end the fighting. But Mark Toner, a State Department spokesman, told reporters that ‘‘the onus was on Hamas’’ to stop the rocket attacks that had provoked Israel.
Southern Israel has been the target of more than 750 rockets fired from Gaza this year that have hit homes and caused injuries. The one that smashed into the top floor of an apartment building in Kiryat Malachi, about 15 miles north of Gaza City, on Thursday killed two men and one woman, according to officials and witnesses at the scene. A baby was among the injured and several Israelis were hospitalized with shrapnel wounds after rockets hit other southern cities and towns, they said.
The apartment house is close to a field in a blue-collar neighborhood and the rocket tore open top-floor apartments, leaving twisted metal window frames and bloodstains.
Nava Chayoun, 40, who lives on the second floor, said her husband, Yitzhak, ran up the stairs immediately after the rocket struck and saw the body of a woman on the floor. He rescued two children from the same apartment and afterward, she said, she and her family ‘‘read Psalms.’’
It was the first time that a building in Kiryat Malachi had been struck. With schools closed after Wednesday’s turmoil, residents said, many people had stayed home with their children.
Residents said people living on the lower floors of the apartment house had taken cover in stairwells, as the police urge residents to do when they hear warning sirens, but those on the top floor apparently had not.
In Gaza, health officials said, those killed Thursday included a 2-year-old boy who had been struck Wednesday in the southern town of Khan Yunis and a 10-month-old girl wounded Wednesday in the Zeitoun area. A 50-year-old man in Beit Lahiyeh, near the northern border, was killed Thursday afternoon when he was buried by sand after a bomb exploded nearby. The others killed Thursday were militants: two Hamas members of a rocket-launching squad in Beit Lahiyeh, and three other Hamas fighters killed in a single strike in Khan Yunis.
The Gazan children who have died so far were aged 10 months, 11 months and 3 years, according to health officials. The victims also include a 19-year-old woman who was six months pregnant, and two men over 55.
Hundreds of Gazans, defying Israeli warnings to stay indoors, took part Thursday in the funeral of Ahmed al-Jabari, the Hamas military leader who was killed the day before in a pinpoint bombing attack on his car in Gaza. Other Hamas leaders, however, did not attend.
As the procession wound its way through the streets from al-Jabari’s home to a mosque, the participants sometimes broke into a jog as Israeli warplanes dropped bombs nearby. Shops were closed in Gaza, and the streets were empty.