Fishermen cautiously sailed out, and market vendors unpacked fruit and vegetables. Outside wrecked mosques, men spread carpets on the sandy ground. Gaza edged back toward normalcy Friday, the first Muslim day of prayer since the end of Israel's war with Hamas.

The United Nations said some 200,000 children who study at U.N. schools were due in class Saturday for the first time since Israel launched its offensive Dec. 27. Thirty schools were damaged in the fighting, U.N. spokesman Christopher Gunness said.

Israel opened its pedestrian crossing into the Gaza Strip, allowing free access for international journalists and humanitarian workers for the first time since before the offensive.

But the U.N. humanitarian chief, John Holmes, said all of Gaza's border crossings needed to be further opened to rush international aid into the besieged coastal strip.

"I hope we can keep at least the humanitarian side of it, the early recovery side, the essential repairs, free of politics, as we always try to do for immediate emergency relief," Holmes said during a tour of Gaza.

Israel and Egypt have blocked most traffic into Gaza since the Islamic militants of Hamas violently seized control of the territory in June 2007 from forces supporting moderate Palestinian President Mahmoud Abbas.

The three-week onslaught, which Israel ordered seeking to halt Hamas rocket attacks, killed 1,285 Palestinians, mostly civilians, the Palestinian Center for Human Rights says. Damage has been estimated at $2 billion. Thirteen Israelis, including three civilians, died during the war, according to the Israeli government.

In Shati, a huge refugee camp in the northern Gaza Strip, hundreds of people crowded the market after Friday prayers, snapping up produce that farmers had been unable to bring out to sell during the bombardment as well as goods smuggled in through tunnels from Egypt.

"I'm buying all I couldn't get during the fighting," said Hosson Bakheet, who planned to cook a big dish of turnips for her family.

She said that was all she could afford because her husband, a construction worker, is unemployed.

Nearby, a farmer was discounting his vegetables because they were damaged in the fighting. "`Phosphorus' cauliflower for only 2 shekels (50 cents)," shouted Adham Taya, who contended the burns on his vegetables were caused by white phosphorus that fell on his fields.

The Israeli army says it has launched an internal investigation into whether its troops inappropriately used phosphorus shells in civilian areas. The intensely hot munitions are used to create smoke screens and to illuminate the night.

On the nearby shore, half the refugee camp's fishing boats went out to sea Friday for the first time since the offensive began, said Slimane Salama, head of Shati's fishermen.

News that Israeli naval vessels blockading the territory wouldn't shoot at the fishing boats came through Arab television stations, he said.

"The problem is there's very little fish" within the three-mile range allowed to the fishermen, Salama said. He said Israeli gunboats fired at fishermen trying to sail farther offshore Friday morning. The military confirmed its vessels fired warning shots at boats.

Despite the signs that life was returning to normal in Gaza, the 6-day-old truce remained fragile. A Palestinian farmer was wounded by Israeli gunfire along the border, Gazan health officials said. Israel's military said it had no information on the incident.

The sides' main demands for a durable cease-fire remained unmet. Israel insists on guarantees that Hamas stop smuggling weapons into Gaza and stop firing rockets at southern Israel, while Hamas wants Gaza's borders open.

Associated Press journalists saw many smuggling tunnels already back in business Thursday along Gaza's border with Egypt.

Despite the Israeli ground offensive and air bombardment, Hamas appeared firmly in control of Gaza, although most of its top leaders remained in hiding.

"The Zionists thought they hammered Hamas, but they are mistaken," Hamas official Mushir al-Masri said in his sermon at the destroyed Khulafa al-Rashideen mosque. "We, the Palestinians, have a strategic weapon that is faith and patience," he said, vowing revenge.

John Ging, head of the U.N. agency that cares for Palestinian refugees, said the war had created "more extremists" on both sides of the conflict. He proposed "independent, objective and credible" investigations into allegations of wrongdoing by both Israel and Hamas during the fighting.

Human rights groups contend Israel used disproportionate force and failed to protect civilians. Israel says it did all it could to avoid civilian casualties. The groups criticize Hamas for firing rockets at Israeli civilians and say it used Gazan civilians as shields.

Gaza-based Hamas officials returned to Egypt to hold talks with Egyptian mediators Sunday that they said would focus on a "working paper" to consolidate the cease-fire.

"We're here in Cairo to talk about arrangements to end the siege on Gaza and to open the border crossings," Salah Bardawil, a Gaza-based Hamas negotiator, told Al-Jazeera television.

Another official said the talks also would address the fate of Israeli Sgt. Gilad Schalit, a soldier who was captured by Gaza militants in 2006.