GAZA CITY, Gaza Strip -- Israel fired two tank shells and several rounds from machine guns as Gazans approached the heavily fortified border with Israel on Sunday, wounding at least 15 youths, a Palestinian health official said. One of the wounded was in critical condition.

The march near the Gaza-Israel border was part of Palestinian commemorations of their uprooting three generations ago during the war over Israel's establishment.

Across the West Bank and Gaza, thousands took to the streets, waving flags and holding old keys to symbolize their dreams of reclaiming property they lost when Israel was created on May 15, 1948.

In Gaza, dozens of marchers approached the border with Israel, and Israeli troops opened fire. The tank shells fell in an empty field several hundred yards (meters) from the group.

Palestinian health official Adham Abu Salmiya said 15 people were wounded by bullets and shrapnel. All of them were under 18 years old, and one was in critical condition, he said.

The Israeli military had no immediate comment.

In a West Bank refugee camp and on the outskirts of Jerusalem, soldiers fired tear gas to break up large crowds of stone throwers. But there were no signs of the mass unrest Israel had prepared for by deploying thousands of troops and sealing the West Bank.

The commemorations mark what the Palestinians call the "Naqba," or "catastrophe." In the fighting over Israel's creation, hundreds of thousands of Palestinians fled their homes or were driven out. The dispute over the fate of the refugees and their descendants, now numbering several million people, remains a key issue in the Mideast conflict.

Websites had urged Palestinians and their supporters in neighboring countries to march on the border with Israel as part of Naqba activities. Security officials tried to block such moves for fear of violence.

In Egypt, the army set up at least 15 checkpoints -- guarded by tanks and armored vehicles -- on the road between the Egyptian town of Al-Arish and the Gaza border city of Rafah, searching cars and checking identification papers and turning back all who were not residents of the area.

A security official said at least 10 activists had been detained. Al-Arish is about 40 kilometers (25 miles) from Rafah.

In Lebanon, meanwhile, thousands of Palestinian refugees gathered in the southern border village of Maroun el-Rass, traveling in buses adorned with posters that read: "We are returning." Many traveled from the 12 crowded and squalid refugee camps in Lebanon where some 400,000 Palestinian refugees live.

Hundreds of Lebanese soldiers, U.N. peacekeepers and riot police deployed heavily in the area, taking up positions along the electric border fence and patrolling the area in military vehicles.

Young Hezbollah supporters wearing yellow hats and carrying walkie-talkies organized the entry to the village and handed out Palestinian flags.

A small group of youths threw stones and tried to advance toward the border, but Lebanese soldiers stopped them and urged them to remain peaceful.

Maroun el-Rass saw some of the fiercest fighting between guerrillas of Hezbollah, which is a militant Shiite Muslim group, and Israeli troops in 2006.

In the occupied territories, leaders of the two Palestinian political camps -- Gaza's Islamic militant Hamas rulers and the internationally backed government in the West Bank -- sent sharply contrasting messages Sunday.

In the West Bank, Prime Minister Salam Fayyad said Palestinians hope this will be the year "in which our people achieve freedom and independence." Fayyad, engaged in building a Palestinian state from the ground up, said it should arise in the West Bank, Gaza and east Jerusalem, the territories Israel captured in the 1967 Mideast war.

In Gaza, Fayyad's Hamas counterpart, Ismail Haniyeh, told thousands of Muslim worshippers during a dawn sermon that Palestinians mark the occasion "with great hope of bringing to an end the Zionist project in Palestine."

Haniyeh's reference to Israel's destruction could prove embarrassing for Palestinian President Mahmoud Abbas, who recently reconciled with Hamas after a four-year split and is trying to market the Islamic militants to the international community as an acceptable political partner.

Inside Israel, police were on high alert for disturbances among the country's Arab minority. In a reflection of the jitters, a deadly traffic accident involving an Arab truck driver in Tel Aviv set off fears that an attack had been carried out.

The truck plowed through a crowded street, crashing into a bus, several cars and pedestrians, killing one and injuring 16 others. Police said the 22-year-old driver claimed it was an accident, but said they were still investigating.


Also contributing to this story were AP reporters Ashraf Sweilam in Al-Arish and Zeina Karam in Maroun el-Rass.