GAZA CITY — Abeer Ghanem, like many Gazans, long struggled to work around the long blackouts that blighted the besieged Palestinian enclave along the Mediterranean Sea.

But with the outbreak of hostilities a week ago between Israel and the Hamas militant group that governs the Gaza Strip, she said, she now gets at best four hours of electricity a day, intermittently. When it comes on, her family scrambles to charge their lights and batteries for the long, sleepless nights punctuated by outgoing Hamas rockets and the thunder of Israeli airstrikes.

“It barely comes,” said the 50-year-old housewife living in the east of Gaza City.

A combination of fuel shortages, damage to the electricity supply lines running from Israel and an aerial bombardment that has torn apart local power lines means that many families are receiving at most three to four hours of electricity a day, according to Gaza’s power company.

“The electricity situation is bad,” said Mohammed Thabet, a spokesman for the Electricity Distribution Co. of Gaza. The only power plant with the capacity to store fuel is running low.

“What we have now for fuel will last for two or three days,” he said.

The plant normally receives most of its fuel through the Kerem Shalom border crossing with Israel, but Israeli authorities closed it during the surge in violence, as they have done during previous bouts of hostility.

The power shortages are compounding the daily misery for Gazans and are also taking a toll on the provision of water, sewage treatment and the ability of hospitals, swamped with casualties, to function. Many homes have rooftop water tanks that require now-dormant electric pumps to fill.

The United Nations warned on Sunday that Gaza was running out of fuel. “Without further provision, fuel is due to run out in the coming days,” said spokesman Jens Laerke. “This will cause significant reduction in electricity supply, again impacting the availability of health, water and sanitation services.”

Before the latest fighting, Gaza’s power company was able to meet half the need of Gaza’s 2 million residents. Both Israel and Egypt have for years sealed the enclave’s borders, limiting outside supplies.

But a week of fighting — during which Israeli airstrikes have pounded Gaza, and Hamas has rained rockets on Israel — has reduced the power supply to at most a quarter of the need.

Israeli authorities have said Hamas damaged the power lines running from Israel but have not provided evidence of this. Five of the 10 lines that normally supply 60 percent of Gaza’s power are out of action.

Distributing power to individual houses is another problem. Power company workers have scrambled to repair power lines, only to see them damaged again. Airstrikes have battered the area’s infrastructure, also splitting open sewage pipes and tearing up roads.

“Water supply, sewage lines, the communications network and electricity have been greatly affected, and there is a shortage of water as well,” said Yahya al-Sarraj, the mayor of Gaza City.

Roshin Shabat, a 43-year-old mother of five children, said she had been receiving a few hours of electricity a day. But since the early hours of Sunday, when ferocious strikes hit her street, she has had none.

To charge their phones, the family members descend to the ground floor of their building, where residents share a small generator for essentials. “There has been suffering for many years from electricity shortages in Gaza, and we have created alternative solutions,” Shabat said. Her family also normally pays to get electricity from another generator to power their apartment. “But now, even the alternative is not available,” she said.

Foreign representatives, including from the United Nations, have been seeking permission for fuel to enter Gaza, along with humanitarian assistance and aid workers.

On Sunday, 48 trucks entered from Egypt, 30 of them filled with cooking gas, 15 with diesel and three with gasoline, according to Tania Hary, executive director of Gisha, an Israeli human rights organization. More was expected Tuesday via the Kerem Shalom crossing, according to Israeli media reports.

Even if supplies resume, Hary said, the crisis has caused millions of dollars in damage to infrastructure. “Even in the best of circumstances, it’s going to take a long time to rehabilitate,” Hary said.

Morris reported from Tel Aviv.