Israeli soldiers shot at Palestinian protesters, wounding about 100 and killing at least one in confrontations with several thousand people demonstrating in the occupied West Bank against the Israeli offensive in Gaza, Palestinian medical officials said.

Some news reports said that as many as two or three Palestinians may have been killed in the clashes, which started Thursday in Qalandia, near the West Bank city of Ramallah, and continued overnight into Friday.

The Israeli military confirmed troops had used "riot dispersal means" against protesters who threw rocks and firebombs at them, and blocked a road with burning tires.

"There are thousands of rioters there," an Israeli army spokeswoman told the AFP news agency. "They are rolling burning tires and throwing Molotov cocktails and fireworks at soldiers and border police.

"The soldiers are responding with riot disposal means," she added, a term used for less-than-lethal weapons such as rubber bullets and tear gas.

The demonstration began after allies of Palestinian President Mahmoud Abbas' Fatah movement marched from Ramallah to the edges of Jerusalem to decry Israel's offensive against Hamas fighters in Gaza.

Israel Radio said the protest appeared to be the largest since the Palestinian uprising that lasted from 2000 to 2005. Protests were reported in Nablus and Bethlehem as well.

Palestinian security and medical officials named one dead man — Mohammed al-Aaraj, 25 — and said he was among the people clashing with soldiers and border police in Qalandia.

Al Jazeera's Dalia Hatuqa, reporting from Ramallah, said, "As flag-carrying demonstrators made their way to the Qalandia checkpoint, which separates the city from Jerusalem, Israeli security forces used live fire, tear gas and rubber-coated steel bullets.

"On Thursday night and overnight Friday, the main road leading to Qalandia checkpoint from Ramallah was carpeted with rocks that mostly young Palestinians threw at Israeli forces.

“Skips and tires were set on fire, and demonstrators hid behind large cement blocks, taking cover as they threw stones and fireworks at soldiers," Hatuqa reported.

More than 150 demonstrators were injured, according to the Palestinian Red Crescent, leading to overcrowding at Ramallah Hospital. Doctors said they had received dozens of live-fire victims and appealed for blood donors.

The protesters in Qalandia said they also wanted to reach al-Aqsa Mosque, to mark Laylat al-Qadr, or Night of Destiny, when Muslims pray through the night as the fasting month of Ramadan nears its end.

But earlier on Thursday, Israeli police had said that because of fears of violent protests, they would bar men under the age of 50 from Jerusalem's flashpoint mosque, which is usually packed as people pray on the last Friday of Ramadan.

Large numbers of police were deployed throughout the city on Thursday night, and police said in a statement that two officers were injured by stone throwers in the vicinity of the mosque.

As of Friday, the Gaza Health Ministry confirmed the death toll had climbed to 815 dead with 5,240 wounded. Israel has lost 32 soldiers, all since July 17, when it widened its air campaign into a full-scale ground operation. Two Israeli civilians and a Thai worker in Israel have also been killed by Palestinian rocket or mortar fire.

Earlier on Thursday, a United Nations school converted to house families displaced by weeks of shelling in Gaza was hit by an apparent Israeli airstrike, killing at least 15 people.

Robert Turner, director of operations in Gaza for the U.N. Relief and Works Agency (UNRWA), confirmed the bombing, saying that no warning was given by Israel before the missile hit.

"There are certainly multiple dead and injured," he told Al Jazeera. The Gaza Health Ministry later said that 15 were confirmed dead and 200 injured.

UNRWA spokesmen Chris Gunness told Al Jazeera, "We gave the Israelis the precise GPS coordinates of the Beit Hanoun shelter. We were trying to coordinate a window [for evacuation], and that was never granted."

He said he could neither confirm nor deny that Hamas fighters were near the building but said Israel and Hamas "must respect the inviolability of U.N. premises and humanitarian law." He called the attack "tragic and appalling."

In a statement U.N. Secretary-General Ban Ki-moon condemned the attack, which also killed some U.N. staff. He said U.N. workers are attempting to arrange "a humanitarian pause in the hostilities so that civilians could be evacuated."

The Palestinian Red Crescent said Israeli shells hit the compound.

The Israeli military said Hamas launched rockets that fell in the area and could have been responsible for the deaths.

"We can't confirm that this is a result of errant fire. In any case, we do not target U.N. facilities," military spokesman Lt. Col. Peter Lerner said. He said the military had urged the U.N. and the Red Cross to evacuate the school for three days before the incident.

The U.N. said it was trying to do just that when the school was hit.

The strike came as the U.N. continued to stress the urgent need for an end to the bombardment of Gaza amid rising civilian deaths and a growing humanitarian crisis.

Earlier Thursday, Valerie Amos, the U.N. undersecretary for humanitarian affairs and emergency relief coordinator, said conditions for civilians living under constant shelling were “dire,” with families running out of food and water.

She said the need for a cease-fire was “vital,” noting that 44 percent of the besieged enclave had become a no-go zone for civilians.

The grave situation on the ground comes a day after Navi Pillay, the U.N. high commissioner for human rights, said during an emergency debate on the crisis that there was “a strong possibility that international law had been violated” during the weeks-long conflict, citing the shelling of homes and hospitals in Gaza. She pointed to both Israel’s military operation and Hamas’ indiscriminate rocket fire.

Pillay’s comments were echoed by the U.N. Human Rights Council, which voted to launch an inquiry into the Israeli offensive's alleged violations of international laws. The Israeli prime minister's office said in a statement on Wednesday that the decision was a “travesty,” adding that Israel had “gone to unprecedented lengths to keep Palestinian civilians out of harm’s way.”

Separately on Thursday, a temporary U.S. ban on commercial flights to and from Israel’s international airport was lifted, giving Israel a partial economic and psychological boost after a Hamas rocket landing near Ben Gurion Airport caused the Federal Aviation Administration to cancel flights.

The airstrike on a U.N. building in Gaza was not the first this week. Gunness said it was the third time this week one of its buildings took a direct hit from Israeli shelling.

Israel has said U.N. schools have been used as havens for armed Palestinians. And U.N. officials have criticized Palestinian groups at various times for using U.N. schools to hide fighters and weapons.

Earlier this week the UNRWA confirmed that an inspection of one of its facilities, a vacant school, found hidden rockets presumed to be from Hamas. They were immediately removed. It was the second time UNRWA discovered rockets in one of its empty schools during the course of the current fighting.

Turner said the building hit Thursday was a school that served as a shelter and that, as far as the UNRWA was aware, there were no projectiles or arms on the site.

A flurry of diplomatic activity to aim for a truce in the fighting continued Thursday.

According to the AFP news agency, Israeli public radio reported on Thursday that the country's security cabinet was expected to meet on Friday to discuss U.S. proposals for a Gaza cease-fire given to Israel and Hamas.

"If Hamas accepts the American proposal, it is not impossible that there could be an Israeli decision to accept it also," public radio quoted an unnamed senior Israeli source as saying.

There was no official confirmation. Israel traditionally does not comment on security cabinet sessions or acknowledge that they take place.

U.S. Secretary of State John Kerry was in Cairo for the second time in 48 hours to attempt to broker a cease-fire between Israel and Hamas.

Kerry was hoping to encourage Hamas to accept an Egyptian-proposed cease-fire deal. He spoke by phone with the foreign ministers of Qatar and Turkey, hoping that both countries would use their influence to encourage Hamas to accept a cease-fire plan.

Khaled Meshaal, Hamas' political chief, who is based in Qatar, reiterated Wednesday that the group would reject any truce without the lifting of Israel's eight-year blockade of Gaza.

"We will not accept any initiative that does not lift the blockade on our people and that does not respect their sacrifices," he said.

The blockade has seen Israel and Egypt severely restrict movement in and out of Gaza since 2007.

Egypt has also been negotiating with some Hamas officials, but relations between the two sides have been strained since Egypt outlawed the Muslim Brotherhood, which has ties to Hamas, after last year's overthrow of President Mohamed Morsi.

The United States is hoping to help broker a humanitarian truce to stop fighting before outstanding issues on the status of Gaza are negotiated.

Al Jazeera and wire services