Clashes erupted as thousands of Gazans marched near the Israeli border in a major protest on Friday, with five Palestinians killed and more than 50 wounded.
Some Gazans estimated the total number of protesters in the tens of thousands, including women and children.
They gathered at multiple sites throughout the blockaded territory, which is flanked by Israel along its eastern and northern borders, AFP correspondents said.
Smaller numbers approached within a few hundreds metres (yards) of the heavily fortified border fence, with Israeli troops using tear gas and live fire to force them back.
The Palestinian Red Crescent reported 201 people wounded from live fire, while the health ministry in the Gaza Strip said four people were killed during the clashes.
Israel's military said: "17,000 Palestinians are rioting in five locations along the Gaza Strip security fence.
"The rioters are rolling burning tyres and hurling firebombs and rocks at the security fence and at (Israeli) troops, who are responding with riot dispersal means and firing towards main instigators."
Earlier in the day, before the main protests began, a Palestinian farmer was killed by Israeli tank fire near the border, the health ministry said.
The Israeli military said the tank fire came after "two suspects approached the security fence ... and began operating suspiciously."
Protesters were demanding hundreds of thousands of Palestinian refugees who fled or were expelled during the war surrounding Israel's creation in 1948 be allowed to return.
Hamas leader Ismail Haniya attended the protest, believed to be the first time he had gone so close to the border in years.
Organisers said the six-week protest would run until the inauguration of the new US embassy in Jerusalem around May 14.
The upcoming embassy move has added to tensions surrounding the march.
Israel announced a "closed military zone in the area surrounding the Gaza Strip," accusing its Islamist rulers Hamas of using the lives of civilians "for the purpose of terror."
It has deployed reinforcements, including more than 100 special forces snipers, for fear of mass attempts to break through the security fence.
Israeli Defence Minister Avigdor Lieberman said in a Twitter post directed to Gazans in both Hebrew and Arabic that "Hamas's leadership is playing with your life."
"Anyone who approaches the fence today will be putting themselves in danger."
US President Donald Trump's recognition of Jerusalem as Israel's capital in December has infuriated Palestinians, who claim its annexed eastern sector as the capital of their future state.
Hamas has fought three wars with Israel since 2008.
- Rare family protest -
Protests along the border are common, often culminating in young Palestinian men throwing stones at Israeli soldiers who respond with tear gas, and rubber and live bullets.
The March of Return protest is different because it is intended to include families with women and children camping near the border for weeks.
Five main camp sites have been set up spanning the length of the frontier, from near the Erez border crossing in the north to Rafah where it meets the Egyptian border in the south.
Cultural events are planned in the larger communal tents, including traditional Palestinian dabke dancing, while tens of thousands of meals will be handed out on Friday, organisers said.
A young couple were married near one of the camps on Thursday evening.
Saeed Juniya had erected a small tent a few hundred metres (yards) from the borderfence east of Gaza City, where he was accompanied by his wife and children.
"We are determined and not scared as we are not doing something wrong. The people are demanding their land and to return to their country," he said.
Organisers say the camps will remain in place until May 15 when Palestinians commemorate the Nakba, or "catastrophe", of the 1948 creation of Israel with the exodus of more than 700,000 Palestinians.
According to the United Nations, some 1.3 million of Gaza's two million residents are refugees or their descendants and the protest is calling for them to be allowed to return to land that is now Israel.
Washington's plans to launch its new embassy around the same time, to coincide with the 70th anniversary of the foundation of the Israeli state, have further stoked Palestinian anger.
Israel's ambassador to the United Nations, Danny Danon, on Thursday labelled the protest an "organised planned provocation" and reiterated "Israel's right to defend its sovereignty and protect its citizens."
The launch of the protests comes as Palestinians mark Land Day, commemorating the killing of six unarmed Arab protesters in Israel in 1976.
Gaza City, Palestinian Territories | AFP