Troops in Israel have fired at crowds of protesters on the country's borders with Lebanon and Syria.
Reports say at least 13 people have been killed and dozens more have been injured, the BBC says.
Tens of thousands of Palestinians and their supporters had marched to the borders to mark the founding of the state of Israel in 1948, which Palestinians call the Nakba, or catastrophe.
Clashes have been taking place at four separate borders or crossing points - at Erez in Gaza, near Ramallah in the West Bank, on the Golan Heights and at the border with Lebanon.
Israel has accused Syria of orchestrating the protests to divert attention from the anti-government uprising there.