Israeli troops opened fire in three separate border locations to prevent crowds of demonstrators, some lobbing rocks, from crossing Israeli frontier lines, in the deadliest such confrontation in years.
Israel called it a cynical provocation inspired by Iran to exploit Palestinian nationalist feeling fuelled by the popular revolts of the "Arab Spring" across the Middle East, and to draw attention from major internal unrest inside Syria, its ally.
The Syrian foreign ministry condemned what it called Israel's "criminal activities", the state news agency SANA said.
Syrian media reports said Israeli gunfire killed two people after dozens of Palestinian refugees infiltrated the Israeli-occupied Golan Heights from Syria.
Security sources on the nearby Lebanese frontier said six Palestinians died when Israeli forces shot at rock-throwing protesters.
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 82 demonstrators approaching the fence with the Hamas-run enclave, medical workers said. In a separate incident, Israeli forces said they shot a man who was trying to plant a bomb near the border. A body was later found.
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, deliberately ran amok with his truck in traffic.
A spokesman for the Islamist Hamas movement in the Gaza Strip, Sami Abu Zuhri, called Sunday "a turning point in the Israeli-Arab conflict" that proved the Palestinian people and Arabs were committed to ending Israeli occupation.
Hezbollah condemned the "Israeli aggression on unarmed civilians in Maroun al-Ras and in the Golan, which constitutes a dangerous violation of human rights," said Hezbollah lawmaker Hassan Fadlallah who was participating at a pro-Palestinian protest in Maroun al-Ras.
"The resistance movement in Lebanon (Hezbollah) will continue to be an advocate for Palestinian national rights and calls on everyone to stand united in confronting Israeli occupation."
"What happened today in Maroun al-Ras and in the Golan is an embodiment of the will of the Palestinian people who are committed to the right of return."
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.
A call had gone out on Facebook urging Palestinians to demonstrate on Israel's borders.
To the south, Egyptian forces arrested six protesters and blocked hundreds of others from marching to its border with Israel, but no frontier police appeared to be on hand in Syria.
"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. "Syria is a police state. People don't randomly approach the border without the approval of the regime."
The border zones are protected by the 1949 Armistice Agreement signed by Israel and its Arab neighbours. A spokesman for the United Nations Disengagement Observer Force, set up on the Israeli-Syrian border after the 1967 Middle East war, said he had "no immediate information" about the rush on the border.
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 flimsy 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, Brigadier-General 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 area.
In the Israeli occupied West Bank, Palestinian youths and Israeli forces clashed for hours at the main checkpoint dividing the Palestinian administrative capital of Ramallah from Jerusalem, a constant flashpoint.
Palestinians hurled rocks and set ablaze tyres and soldiers fired tear gas, rubber bullets and tear gas to drive them away from the Qalandia checkpoint.
Several hundred protesters, some of whom were said they had come from Hebron in the southern West Bank and Jenin in the northern West Bank to join the protest.
Hamas spokesman Taher Al-Nono praised the "crowds we have seen in Palestine, Egypt, Syria, and Lebanon" as evidence of "the imminent victory and return to the original homes as promised by God".
US-brokered Peace talks between the Palestinians and Israel broke down last year and no new negotiations are in the offing, with the U.S. Middle East peace envoy George Mitchell announcing his resignation on Friday.