Violence erupted on Israel's borders with Syria, Lebanon and Gaza on Sunday, leaving at least eight dead and dozens wounded, as Palestinians marked what they term "the catastrophe" of Israel's founding in 1948.
Israeli troops shot at protesters in three separate locations to prevent crowds from crossing Israeli frontier lines in the deadliest such confrontation in years.
Israeli and Syrian media reports said Israeli gunfire killed four people after dozens of Palestinian refugees infiltrated the Israeli-occupied Golan Heights from Syria, along a disputed border that has been quiet for decades.
Witnesses on the nearby Lebanese frontier said four Palestinians were killed after Israeli forces fired at rock-throwing protesters to prevent them from crossing the border.
The Lebanese army had also earlier fired in the air in an attempt to hold back the crowds.
On Israel's tense southern border with the Gaza Strip, Israeli gunfire wounded 60 Palestinians as demonstrators approached Israel's fence with the Hamas Islamist-run enclave, medical workers said.
In Tel Aviv, Israel's commercial hub, a truck driven by an Arab Israeli slammed into vehicles and pedestrians, killing one man and injuring 17 people.
Police were trying to determine whether the incident was an accident or an attack. Witnesses said the driver, who was arrested, ran amok with his truck in downtown traffic.
Israeli security forces had been on alert for violence on Sunday, the day Palestinians mark the "Nakba," or catastrophe, of Israel's founding in a 1948 war, when hundreds of thousands of their brethren fled or were forced to leave their homes.
In the Druze village of Majdal Shams, on the Golan Heights captured by Israel from Syria in 1967, Mayor Dolan Abu Salah said between 40 and 50 Nakba demonstrators from Syria tore through the frontier fence.
Hundreds of protesters flooded the lush green valley that marks the border area, waving Palestinian flags. Israeli troops attempted to mend the breached fence, firing at what the army described as infiltrators.
"We are seeing here an Iranian provocation, on both the Syrian and the Lebanese frontiers, to try to exploit the Nakba day commemorations," said the army's chief spokesman, Lieutenant-Colonel Yoav Mordechai.
Syria is home to 470,000 Palestinian refugees and its leadership, now facing fierce internal unrest, had in previous years prevented protesters from reaching the frontier fence.
"This appears to be a cynical and transparent act by the Syrian leadership to deliberately create a crisis on the border so as to distract attention from the very real problems that regime is facing at home," said a senior Israeli government official who declined to be named.
In a Nakba protest in the occupied West Bank, Palestinian youths threw rocks at Israeli soldiers, who fired tear gas and rubber bullets in a clash at the Israeli military checkpoint outside the city of Ramallah -- a constant flashpoint.
A Palestinian teenager was shot dead during protests in Jerusalem on Friday. Police said it was unclear who had shot him and they were investigating.
That shooting took place in the tense neighborhood of Silwan in East Jerusalem, where violence regularly breaks out between Palestinian stone throwers and Israeli police and Jewish settlers.
Palestinians want East Jerusalem as the capital of the state they intend to establish in the West Bank and Gaza Strip.