GAZA CITY — Sana'a al-Kulak spent the night under the rubble. It was hard to breathe; her leg was trapped. Her son, stuck beside her, managed to get out his phone and call for help.

“We tried to hold out,” she said.

It was around five hours after Israeli airstrikes flattened their home before al-Kulak, 56, and her 24-year-old son, Mohammed, were pulled out by rescuers. It wasn’t until she got to the hospital that she learned the shattering news.

Her husband, their two sons, a daughter, daughter-in-law and a 1-year-old grandchild had all been killed, alongside at least 11 other members of her extended clan that had lived across two four-story buildings in Gaza’s Wehda Street.

Both buildings and another in the neighborhood were reduced to rubble early Sunday. Forty-two people, including 16 women and 10 children, were killed in the predawn strikes, according to Gaza health authorities, the deadliest incident in the current round of violence between Israel and Hamas. A list of 30 of the dead released by the Mezan Center for Human Rights, a local advocacy group, included 17 members of the al-Kulak family.

The Israeli military said an initial investigation showed the casualties had been “unintended.” The aim of the strike, it said, was Hamas “military infrastructure” under the street outside. The seven-day conflict, during which Hamas has fired more than 3,100 rockets toward Israel, has seen airstrikes in Gaza of a ferocity that people here say surpasses that of previous conflicts.

Israeli airstrikes in Gaza killed 42 people on May 16 as hostilities entered their second week amid increasing international calls for a cease-fire. (Reuters)

Israeli Prime Minister Benjamin Netanyahu said Sunday that the Israeli military had carried out attacks on more than 1,500 targets in seven days. The strikes in the center of the city have struck terror in Gaza.

Gaza’s health ministry says 192 residents, including 58 children and 34 women, have died in the last week. In Israel, 10 people have died as Hamas has fired of intense barrages of rockets and missiles toward cities in an attempt to overwhelm air defenses.

Sana’a al-Kulak said she woke at around 1 a.m. Sunday to the sound of bombing. The house was full. A son who ordinarily lives in northern Gaza had brought his wife home to stay with his parents in central Gaza, thinking it’d be safer.

The bombardment was so frightening that some family members began to leave their third floor apartment for lower floors. Mohammed said his mother was at the door while others were on the stairs. “They didn’t reach the first floor,” he said.

The Israeli military says it was an indirect building collapse. Mohammed said he believes the building suffered a direct hit. It collapsed around Mohammed and his mother.

“I tried to call the police, but the connection was very bad,” he said. He called a friend and told him they were trapped. “I didn’t know about the rest of the family,” he said. He was dragged out at 6 a.m.; his mother was rescued half an hour later.

Mohammed Abu Mughaiseeb, deputy medical coordinator for Doctors Without Borders in Gaza, lives half a mile away but thought the strike was right outside. “My house was completely shaking,” he said. “It was about 15 minutes — intense bombing, continuous duh-duh-duh-duh-duh.”

One of the group’s trauma and burn treatment clinics nearer to Wehda Street was damaged. For Mughaiseeb, as for most Gazans, it’s his fourth war. “In 2014, the bombing was at the edges and then, at the end, inside,” he said. “But not in the same way it’s happening now. Now even the streets are bombed.”

Israeli commanders say their targets have included what it terms the “Gaza Metro” — Hamas’s extensive network of tunnels that snake under the city. The military has struck to degrade the group’s rocket launching capacity; some attacks have been in the heart of Gaza City. Israel accuses Hamas of using civilians as human shields.

The operation is the first test of a new “victory concept” espoused by Lt. Gen. Aviv Kochavi, Israel’s chief of staff. It aims to turn the Israeli military into what one Israeli Defense Forces document describes as a “significantly more lethal, networked war machine that can destroy enemy capabilities in record time and with the lowest possible casualties” and to shift away from the old methods known as “mowing the lawn” — military campaigns that buy a little respite — to more decisive victories. Part of it is adapting to more quickly identify targets in dense urban areas such as Gaza. “This,” Lt. Col. Jonathan Conricus, an Israeli military spokesman, said in a recent briefing, “is the doctrine and concept being applied.”

For those in the city, it has felt as if there is no escape.

Aya Aloul’s building partially collapsed. The 25-year-old had pulled her mattress into her parents’ room to sleep at the beginning of the conflict last week. She was lying in bed chatting on WhatsApp early Sunday when the bombing started. “Within a second, it was black. I couldn’t see anything, and I found myself on the ground in the street,” she said.

She was covered in rubble. “I didn’t know how I could bring the strength to remove all the rubble on me,” she said. She couldn’t free her mother, who was later pulled out by rescuers. Her father, a doctor, did not survive.

Civil defense rescue workers in orange vests were still pulling bodies out of the rubble on Sunday afternoon and loading them into white body bags. Yellow diggers pulled up concrete and twisted metal to get to families trapped underneath.

Parts of Wehda Street were collapsed and cracked. One rescuer, pulling out a newly discovered body, said he had been working since around 1 a.m. He said he had rescued 10 people alive and retrieved four bodies.

Maryam al-Kulak, a daughter of Sana’a, rushed to the nearby Shifa Hospital when she heard that her family home was destroyed. “There were bodies and some injured people,” she said. “I waited, crying.” The bodies of her father and one brother arrived first. Then her mother and Mohammed were brought in alive. “They bombed the house without warning, and without any reason,” she said. “There were civilians in it who do not deserve what happened to them.”

Sana’a said she doesn’t feel a sense of revenge. “I just want the war to end,” she said.

She thanks God that she’s alive. “But now there is no sense in life without my husband and children.”

Morris reported from Tel Aviv.