Dozens of people have been injured in the Gaza Strip as thousands of Palestinians and activists marched to mark "Nakba Day", or Israel's 1948 founding, amid tight Israeli security.
A group of Palestinians, including children, were shot by the Israeli army after crossing a Hamas checkpoint and entering what Israel calls a "buffer zone" - an empty area between checkpoints where Israeli soldiers generally shoot trespassers, Al Jazeera correspondent Nicole Johnston reported from Gaza City.
Johnston said tank shelling and artillery fire were also heard from the Israeli border with the Gaza Strip.
Reports said at least 45 Palestinians were wounded in northern Gaza as Israeli troops opened fire on a march of at least 1,000 people heading towards the Erez crossing between the Gaza Strip and Israel.
In south Tel Aviv, one Israeli man was killed and 17 were injured when a 22-year-old Arab Israeli driver drove his truck into a number of vehicles on one of the city's main roads.
Israeli police spokesman Micky Rosenfeld said the driver, from an Arab village called Kfar Qasim in the West Bank, was arrested at the scene and is being questioned.
"Based on the destruction and the damage at the scene, we have reason to believe that it was carried out deliberately," Rosenfeld said. He did not believe the motive was directly linked to the anniversary of the Nakba.
West Bank clashes
One of the biggest demonstrations was held near Qalandiya refugee camp and checkpoint, the main secured entry point into the West Bank from Israel, where about 100 protesters marched, Al Jazeera correspondent Nisreen El Shmayleh reported from Ramallah.
Some injuries were reported from tear gas canisters fired at protesters there, El Shmayleh said.
Small clashes were reported throughout various neighbourhoods of East Jerusalem and cities in the West Bank, between stone-throwing Palestinians and Israeli security forces.
Israeli police said 20 arrests were made in the East Jerusalem area of Issawiyah for throwing stones and petrol bombs at Israeli border police officers.
About 70 arrests have been made in East Jerusalem throughout the Nakba protests that began on Friday, two days ahead of the May 15 anniversary, police spokesman Rosenfeld said.
Tensions had risen a day earlier after a 17-year-old Palestinian boy died of a gunshot wound suffered amid clashes on Friday in Silwan, another East Jerusalem neighbourhood.
Police said the source of the gunfire was unclear and that police were investigating, while local sources told Al Jazeera that Ayyash was shot in random firing of live ammunition by guards of Jewish settlers living in nearby Beit Yonatan.
Lebanon and Syria
About 20,000 people are expected to gather by the end of Sunday at Ras Maroun, a Lebanese border town.
Matthew Cassel, a journalist en route to Lebanon's southern border with Israel, tweeted that dozens of buses were departing Nahr al-Bared and Baddawi refugee camps in northern Lebanon.
Some activists tweeted that the Lebanese and Jordanian authorities were prohibiting protesters from nearing the borders. The information could not be independently verified.
Israeli army radio said dozens were wounded in a shooting incident on the Israeli-occupied Golan Heights, an area bordering with Syria.
Palestinian refugees from Syrian side of the border were shot for trying to break through the frontier fence, the radio report said.
Israeli army spokepersons' office said an Israeli army patrol shot in the air in an effort to desist "people trying to cross into Israel and trying to damage the fence." There was no comment on reports of the injured.
'End to Zionist project'
Israeli Prime Minister Binyamin Netanyahu condemned Sunday's demonstrations.
“I regret that there are extremists among Israeli Arabs and in neighbouring countries who have turned the day on which the State of Israel was established, the day on which the Israeli democracy was established, into a day of incitement, violence and rage", Netanyahu said at the start of a cabinet meeting.
"There is no place for this, for denying the existence of the State of Israel. No to extremism and no to violence. The opposite is true", he said.
Earlier Sunday Ismail Haniyeh, prime minister of Hamas-controlled Gaza, repeated the group's call for the end of the state of Israel.
Addressing Muslim worshippers in Gaza City on Sunday, Haniyeh said Palestinians marked this year's Nakba "with great hope of bringing to an end the Zionist project in Palestine".
"To achieve our goals in the liberation of our occupied land, we should have one leadership,'' Haniyeh
said, praising the recent unity deal with its rival, Fatah, the political organisation which controls the West Bank under Palestinian president Mahmoud Abbas' leadership.
Meanwhile, a 63 second-long siren rang midday in commemoration of the Nakba's 63rd anniversary.
Over 760,000 Palestinians - estimated today to number 4.7 million with their descendants - fled or were driven out of their homes in the conflict that followed Israel's creation.
Many took refuge in neighbouring Lebanon, Jordan, Egypt and elsewhere. Some continue to live refugee camps.
About 160,000 Palestinians stayed behind in what is now Israeli territory and are known as Arab Israelis. They now total around 1.3 million, or some 20 percent of Israel's population.