ASHKELON, Israel — Airstrikes left neighborhoods in Gaza trembling, killing at least two dozen people, and rockets rained on cities in Israel, including Tel Aviv, as some of the worst fighting between Israelis and Palestinians in years showed no signs of abating on Tuesday.
The immediate trigger was a police raid on an Islamic holy site in Jerusalem the day before, but by Tuesday the conflict had grown far broader, with civilians on both sides of the border paying a heavy cost.
By Tuesday night, 30 Palestinians had been killed in Israeli airstrikes, including 10 children, and 203 others were wounded, according to Gaza health officials. One airstrike toppled a tower that houses the offices of several Hamas officials.
In Israel, at least three people were reported killed and at least 100 wounded.
Two of the deaths followed strikes on the seaside city of Ashkelon, just 13 miles up the coast from Gaza. And shortly after 9 p.m., militants fired another barrage toward Tel Aviv, Israel’s second-largest city, with one rocket hitting an empty bus south of the city. One person was killed, the authorities said, and 11 people were reported wounded.
As multiple salvos of rockets streaked out of Gaza in rapid succession, one hit a school in Ashkelon. A giant fire raged on the outskirts of the city, where an oil facility was hit. The school was empty at the time because the Israeli authorities had ordered all schools within a 25-mile radius of Gaza closed in anticipation of rockets.
In a speech recorded in Qatar and aired on a Hamas-affiliated television channel, a senior Hamas political leader, Ismail Haniya, struck a triumphant tone.
“We have managed to create an equation linking the Jerusalem and Gaza fronts,” he said. “They are inseparable. Jerusalem and Gaza are one.”
Mr. Haniya said he had received calls from Egypt, Qatar and the United Nations about working toward a cease-fire, but argued that Israel had set off the violence and should be held responsible for ending it.
For his part, Israel’s prime minister, Benjamin Netanyahu, also sounded a note of defiance.
“Hamas and Islamic Jihad have paid, and will pay, a very heavy price for their aggression,” he declared in a late-night address to Israelis that suggested the hostilities might not end any time soon.
“This campaign will take time,” Mr. Netanyahu said.
The Israeli military, prepared for the latest eruption of cross-border fighting with militant groups in Gaza, designated a code name for its operation just hours after the deadly violence began: Guardians of the Walls, a reference to the ancient ramparts of the Old City of Jerusalem. The militant groups had their own code name for their campaign: Sword of Jerusalem.
By early Tuesday morning, barely 12 hours after Hamas, the Islamist militant group that holds sway in Gaza, had launched a surprise volley of rockets toward Jerusalem, Israel had carried out at least 130 retaliatory airstrikes in the Palestinian coastal territory, according to an Israeli military spokesman, Lt. Col. Jonathan Conricus. Militant groups had fired nearly 500 rockets into Israel by the afternoon, according to military officials.
Colonel Conricus said early Tuesday that 15 militants had been killed in strikes by jets and unmanned drones.
He did not confirm or reject the reports of civilian deaths, adding, “We are doing everything possible to avoid collateral damage.”
Hamas said that a number of its militants had been killed and that some others had been reported missing in an Israeli attack on a target, without giving further details.
Although the intensity of the fighting seemed to have waned slightly during the night, Colonel Conricus said that the military’s air campaign was still in its “early stages.” Journalists were unable to enter the coastal enclave on Tuesday morning because of rocket fire near the crossing point from Israel.
The Israeli military said in a statement that it had reinforced its troops and was “prepared for a variety of scenarios.”
The cross-border military conflict escalated rapidly on Monday evening after weeks of rising tensions and confrontations between the police and Palestinian protesters in and around the ancient center of Jerusalem, including at the sacred Aqsa compound, known to Jews as the Temple Mount and to Muslims as the Noble Sanctuary. Hamas, casting itself as the Palestinian defender of the contested city, had issued a series of threats and ultimatums.
The immediate trigger appears to have been a police raid at the mosque compound on Monday morning to disperse crowds and stone-throwing protesters with tear gas, stun grenades and rubber-tipped bullets. More than 330 Palestinians were wounded, at least three critically, according to the Palestinian Red Crescent. At least 21 police officers were wounded.
But as the conflict expanded and the airstrikes began, it quickly became deadly.
In Beit Hanoun, northern Gaza, the Masri family was grieving for two young boys who were killed on Monday evening. Ibrahim, 11, and Marwan, 7, had been playing outside their home when a missile struck, according to their uncle, Bashir al-Masri, 25.
For Mr. Masri, the attack showed that Israel had no concern for civilian life.
“They target buildings with children, they target ambulances, they target schools,” he said by telephone. “And all the world, beginning with America, says that people in Gaza are terrorists. But we are not terrorists. We just want to live in peace.”
He also called on Israel to end a blockade on Gaza that has placed heavy restrictions on goods and materials, lest they be used to make weaponry. The blockade, coupled with similar restrictions by Egypt, has crippled Gaza’s economy and led to high unemployment.
“God knows how we live in Gaza — and the No. 1 reason is the Israeli siege,” said Mr. Masri, who is one of the roughly 50 percent of Gazans without work. “They want to kill us. But they cannot.”
About a dozen miles north, in a suburb of Ashkelon, residents were startled shortly before 6 a.m. by a rocket strike on an apartment block. The rocket crashed through the window of a third-story apartment in Kohav HaTzafon, an area that is home to mostly Russian immigrants, and it shattered several others with its impact.
Six people wounded by the direct hit on the building, four of them from one family, were transported to Barzilai Medical Center, the main hospital in Ashkelon. The parents were in moderate to serious condition and their two children, ages 6 and 12, along with the two others were lightly wounded, according to the hospital.
The father of the family, Edward Weinstock, speaking on public radio from his hospital bed a few hours later, said that the rocket had landed in his son’s bedroom and that the family had not had time to reach the safety of the stairwell. “Lucky he was not there,” he said of his son. “I found myself lying on the floor, not understanding what had happened.”
Sitting among the shattered glass in her son’s second-floor apartment, Maria Nagiv, 61, said she understood little about the events that had led to the attack.
“What happened in Jerusalem?” she asked as shards crunched beneath her feet. “I haven’t been following anything about that.”
She added: “All the world says that the Jews make trouble. But what have I done wrong? I didn’t do anything, and they still send us bombs.”
A few minutes later, the sirens sounded again, warning of another rocket nearby.
The Iron Dome, an Israeli antimissile defense system, successfully intercepted about 90 percent of rockets headed for populated areas, according to military officials.
Many of the rockets fired out of Gaza were short-range projectiles, primarily aimed at civilian communities within a few miles of the border.
The Israeli military said that its targets had included the weapons manufacturing sites of Hamas and Islamic Jihad, another militant group, as well as military facilities and two offensive tunnels. A Hamas battalion commander who was at home in a residential apartment building was also targeted, according to the military.
Neither the location nor the condition of the person said to be a battalion commander was immediately clear.
But health officials said that the bodies of three civilians had been removed from the ruins of the building.
Two of them were said to be members of a family that lived three floors below the apartment of the person alleged to be a commander — Amira Soboh, 58, and her son Abdelrahman, 17, who had cerebral palsy. They were killed by falling rubble, said Ms. Soboh’s older son, Osama Soboh.
Mr. Soboh, a 31-year-old civil servant, questioned why Israel had targeted a civilian building. “It’s not a military barracks, it’s not posing any danger to Israel,” he said. “This was an old woman with a child with cerebral palsy.”
“This is my mom,” he said. “It’s a very hard thing to say farewell to the most precious person you have on Earth.”
The military wing of Hamas, known as the Qassam Brigades, issued a statement after the strike on the building warning Israel that if it kept hitting civilian houses, “We will turn Ashkelon into hell.”
The first barrage of rockets quickly followed.
As the day wore on, there seemed no end in sight. Israel struck more targets in Gaza. Hamas hit back with the extensive salvos of rockets that reached civilian areas in Ashdod.
In a phone interview with a state-funded broadcaster, an Ashkelon City Council member, Amichai Siboni, paused the conversation three times as he sought the nearest bomb shelter.
“There is a siren right now, I am looking for a safe room in a supermarket, I see around me elderly shoppers getting down to the floor,” Mr. Siboni said as he searched. “They are anxious and holding on to each other on the ground.”
Iyad Abuheweila contributed reporting from Gaza City, and Myra Noveck from Jerusalem.