When members of the Sultan family ran from their home as an Israeli tank shelled its northern wall, there was no time to shut the front door. There was also no need.

The house, which family patriarch Samir al-Sultan began building at the age of 15, was all but destroyed as Israeli forces advanced into the Gaza Strip in early January, turning the house's contents into a mangled mess of glass and mortar.

With no home to return to and no prospects for rebuilding, the Sultans on Thursday were among the thousands of Palestinians in Gaza searching for somewhere to go.

Israel's 22-day war on Hamas, the Islamist movement that controls Gaza, forced 50,000 people into shelters, according to U.N. officials. They say 15,000 remain in such facilities because of damage to their homes -- with countless more finding refuge in the care of relatives.

In the aftermath of the war, there are scenes of devastation at nearly every turn in Gaza. Whole blocks are pockmarked by bullet holes. The earth craters where tall buildings once stood. Mourning tents line the roadways.

Even as many Gazans attempt to return to a normal life -- going to work and shopping in the market -- those displaced during the fighting remain a prominent part of the landscape: By day they return to what is left of their homes to keep watch, building fires to stay warm and picking through the debris in search of valuables. By night they sleep in the living rooms of aunts and uncles or, as in the case of the Sultans, in crowded elementary-school classrooms that have become a temporary refuge -- though for how long no one knows.

The Sultans have moved three times in the 19 days since they fled their home, the family said, giving a more detailed account of their travails than they earlier provided The Washington Post.

In one U.N.-run shelter, their 20-year-old son Abdullah visited the bathroom on the night of Jan. 5 to fetch his mother some water. An Israeli airstrike killed him on the spot, along with two of his cousins.

They are among the estimated 1,300 Palestinians who died in the war, with 5,000 more injured. Thirteen Israelis were killed after Israel began its assault Dec. 27, citing persistent Hamas rocket fire into southern Israel.

The Israeli military says it took all possible precautions to avoid civilian casualties as it fought an enemy embedded among the populace, and also attempted to spare the homes of those who were not involved in violence against Israel.

The Sultans say they fit that description, but their building was fired on nonetheless. The destruction of the family home, which they discovered after the cease-fire, has deepened their sense of grievance.

"They destroyed everything," said Intisar al-Sultan, 50, who lived in the three-story house with her husband, three sons, daughter-in-law and grandson. "They kept nothing. No trees. No animals. Even our clothes are gone. We don't know where to go. We have nothing."

During a visit to Gaza on Thursday, U.N. humanitarian chief John Holmes said finding shelter for those displaced by the war was among the most urgent needs of the recovery effort. He called for Gaza's crossings -- which have been largely sealed shut for the past 19 months as a result of an Israeli blockade against Hamas -- to open to allow in building supplies. "Goods have to be able to get in freely and in the right quantities, including construction materials, so that reconstruction can start," he said.

But the question of who will fund and manage the reconstruction has become a sensitive one. There are still no firm plans for how it will proceed, and there is as yet little evidence of any rebuilding on the ground.

Hamas said Thursday that beginning on Sunday, the group intends to distribute up to $5,000 in cash to families whose homes have been destroyed. Families whose homes have been significantly damaged, but are still standing, would get about half that, Hamas spokesman Taher al-Nono told reporters in Gaza.

The Palestinian Authority, which holds sway in the West Bank but has not had an organized presence in Gaza since June 2007, when Hamas ousted forces loyal to the Fatah party that dominates the authority, said Israel so far had blocked it from sending assistance.

U.S. officials have signaled that they would like for the Palestinian Authority to take the lead in the reconstruction in order to enhance its battered image among Palestinians. Hamas is considered a terrorist organization by Israel, the United States and the European Union.

Regardless of who manages the effort, the United Nations says it intends to be a major player in the reconstruction, which it is estimated will cost more than $2 billion.

Christopher Gunness, spokesman for the U.N. Relief and Works Agency in Gaza, said rehabilitating homes that are damaged but still livable will be among the first priorities. Others will have to wait. "If your house is completely flattened, that will come later," he said. But until then, he said, "nobody is going to be thrown out on the streets."

Still, with most shelters packed to the point where 30 people are sleeping in a single classroom, the standards for who can stay and who must go are becoming stringent.

"We have two types of families here -- those whose homes were completely destroyed and those whose homes were half-destroyed," said the manager at one U.N. shelter, who cited agency policy in not giving his name. "If you have at least one room left in your home that's livable, you have to leave. The ones whose homes were completely destroyed can stay."

The Sultans can stay. Although technically their home still stands, the entire northern wall is gone, and the ceilings contain jagged cracks that reveal glimpses of the floors above.

So far, family members say, no one has offered to help them rebuild. The $5,000 promised by Hamas would not go far; in Gaza, where construction materials are scarce, even a relatively modest house can cost $100,000 or more to build.

And in any case, Samir Sultan, 52, said he would be reluctant to accept money from the group. Already, he has turned down offers by both Hamas and Fatah to pay for his son's funeral. His son, he said, was not a member of either party, and he said the family has not been involved in any violence against Israel.

He said he forbade Palestinian fighters to use his land to fire rockets against Israel, although he acknowledged that Hamas had a presence in the area. "My neighbor's house belongs to Hamas. And nothing happened to them," he said, pointing to a nearby home seemingly unscathed by the war as he kicked at a shattered bathroom sink in what remains of his second-floor bathroom.

The Sultan home in the northern town of Beit Lahiya overlooks the Mediterranean Sea to the west, farmland to the east and Israel to the north. For 12 years, Samir Sultan worked in Israel at an aluminum factory, learning Hebrew and earning enough money to significantly expand a small house he had built on his father's bean fields.

But eight years ago, amid rising violence, the border with Israel was shut and Sultan lost his job. Since then, he has eked out a meager living by selling fruits and vegetables from the back of a donkey cart.

On the morning of Jan. 3, Sultan took a white flag with him as he entered his back yard to feed the donkey. As he was returning to his house, he said, shots came from the fields to the north. The donkey fell, killed in an instant, and Sultan and his family sprinted down a narrow, sandy path to his daughter's house. Three days later, advancing Israeli tanks forced them to flee again, this time to a U.N.-run school in Gaza City.

"We were told that in the shelters, we would get protection," said Intisar Sultan, as she clutched a framed photo of her youngest son and softly cried. "But they kicked us out of our homes, and they followed us to the shelters to kill our sons."

She sent Abdullah to get water the night of Jan. 5 and never saw him again. Witnesses said his body was cut into dozens of pieces by an Israeli missile strike.

Maj. Avital Leibovich, a spokeswoman for the Israel Defense Forces, said that the matter was under investigation but that "what we understand is that there was an exchange of fire in that area." In general, she said, Hamas adopted a strategy of taking cover in urban neighborhoods and posting fighters and explosives in schools and medical centers.

The United Nations has denied that its schools were used as a cover for fighters.

After Abdullah was killed, the Sultans moved to another U.N. school, where they remained Thursday afternoon, still wearing the same clothes they had fled in. They sleep on thin mattresses, with dozens of extended family members sharing the same classroom floor. Infections are common at the school. A grandson, who is 18 months old, has been sick with a fever for a week, family members say.

As the sun set in Gaza on Thursday, the shelter manager said it would likely be the last night that anyone slept there. The students need their school back, he said. Those who still lack a home would have to be transferred somewhere else, though he did not know where.