Gaza activists burned tyres and threw stones near the sealed border with Israel in a seventh weekly protest aimed at removing a decade-old blockade of their territory.
Israeli soldiers fired live bullets and tear gas volleys from the other side of the border fence.
Fifteen protesters were wounded by live fire, four of them seriously, including a 16-year-old boy shot in the head, Gaza health officials said. Two dozen others were overcome by tear gas.
The protest came just three days ahead of what the leader of Gaza’s ruling Hamas group has said will be a march by tens of thousands who could burst through the border fence into Israel.
The crowd on Monday will be unarmed and peaceful, but like a “starving tiger” in pent-up anger and unpredictability, Yehiyeh Sinwar told reporters.
Israel has warned that it will prevent any border breach. It has stuck to its open-fire policies, such as targeting “main instigators” and those approaching the fence, despite growing international criticism.
Israel said it has a right to defend its border and has accused Hamas of using the protests as a cover for attacking the border. Rights group say the use of potentially lethal force against unarmed protesters is unlawful.
Since the Hamas-led marches began in late March, 40 Palestinian protests have been killed and more than 1,700 wounded by Israel army fire. The protests, driven by despair among Gaza’s two million people, are part of a campaign to break the blockade imposed by Israel and Egypt after the Islamic militant Hamas overran Gaza in 2007.
There are growing concerns that if Israel and Hamas dig in, a widespread border breach in coming days could lead to large numbers of casualties.
Monday’s border march is meant to protest against the planned move of the US Embassy in Israel from Tel Aviv to contested Jerusalem that day.
The embassy’s inauguration comes five months after President Donald Trump recognised Jerusalem as Israel’s capital, a move that outraged Palestinians as blatantly pro-Israel.
The Israeli-annexed eastern sector of Jerusalem is sought as a future Palestinian capital — at least by those supporting Hamas’ political rival, West Bank-based Palestinian President Mahmoud Abbas.
Hamas seeks an Islamic state in the entire historic Palestine, including what is now Israel, but has said it is ready for a long-term truce.