Funerals are to be held in Gaza for 58 people killed on Monday when Israeli troops opened fire on Palestinian protesters, in the deadliest day of violence there since a war in 2014.
The burials coincide with the 70th anniversary of what Palestinians call the Nakba – the mass displacement of Palestinians after Israel's creation.
Israel's military said it was preparing for further confrontations on Tuesday.
But Palestinian groups indicated they intended to rein in the protests.
Monday's violence came as the US inaugurated its first embassy in Jerusalem, a controversial move that broke with decades of US policy and incensed Palestinians.
Palestinians claim East Jerusalem as the capital of a future Palestinian state, and see the US move as backing Israeli control over the whole of the city – which Israel regards as its indivisible capital.
Palestinian officials said that, as well as those killed, about 2,700 people were injured in Monday's violence – which they condemned as a massacre.
Israeli PM Benjamin Netanyahu said his military was acting in self-defence against Gaza's Islamist rulers, Hamas, who he said wanted to destroy Israel.
What happened at the Gaza border?
Palestinians were demonstrating on Monday as they have been for seven weeks, as part of a protest orchestrated in part by Hamas and branded the "Great March of Return".
But Monday's protests – and those planned for Tuesday – mark the anniversary of Israel's creation in 1948 and commemorate the hundreds of thousands of Palestinians who subsequently fled their homes or were displaced in the war that followed.
Israel said some 40,000 Palestinians had taken part in "violent riots" at 13 locations along Israel's security fence along Gaza's eastern border.
Palestinians hurled stones and incendiary devices and approached the border fence. Israeli snipers fired live ammunition at protesters and used tear gas dispersed from drones.
What is Hamas?
Mr Netanyahu defended the military action. "Every country has an obligation to defend its borders," he said.
"The Hamas terrorist organisation declares its intention to destroy Israel and sends thousands to breach the border fence in order to achieve this goal. We will continue to act with determination to protect our sovereignty and our citizens."
An Israel Defense Forces (IDF) spokesman said soldiers had fired on people carrying out "terrorist activity and not on demonstrators, who were dispersed by usual means such as tear gas and according to the rules of engagement".
Announcing three days of mourning, the West Bank-based Palestinian Authority President Mahmoud Abbas said: "Today once again, the massacres against our people continue."