A Palestinian teenager has been shot dead close to southern Gaza's border, Palestinians say, as at least five other Gazans were wounded elsewhere.
Muhammad al-Faramawi, 15, was killed on Tuesday by Israeli fire near Rafah, the Hamas-run health ministry said.
The Israeli military said it was not aware of hitting anyone, but military sources said warning shots had been fired in the area.
At least five Gazans were injured at protests elsewhere along the border.
Several rallies were held in Gaza border areas on Tuesday to mark Palestinian Land Day, which commemorates the deaths of six Palestinians with Israeli citizenship who were killed at a demonstration over land seizures 34 years ago.
Early reports said Muhammad al-Faramawi had died during a protest, but later reports said the incident occurred before the demonstrations took place, and the main protests were held further north.
Israel enforces a buffer zone close to the border, where it says Palestinians frequently try to plant explosives and have launched attempts to kidnap Israeli soldiers.
Troops have in the past fired at Palestinians in the zone.
The Israeli military said it had acted in "accordance with procedures" to deter protesters who had approached the fence.
It was initially reported that a Palestinian doctor told reporters that medics were not able to reach the body of the boy in time because of ongoing "clashes".
An official from the Hamas-run ministry of health said the teenager "was left bleeding for hours" before paramedics were able to get Israeli permission to evacuate him.
However, there has been speculation over whether the boy could have died in an intra-Palestinian dispute.
The Maan news service quoted unnamed Palestinian sources who said the boy's death "may have been an internal matter", without giving further details.
Further north, near the town of Khan Younis in the Gaza Strip, hundreds of demonstrators marched to the border and hurled rocks at Israeli troops, who responded with live fire, witnesses said.
Five people were injured in such protests, Palestinian medical sources said.
Last week, Israeli tanks advanced briefly into the Gaza Strip following clashes in which two Israeli soldiers and two Palestinian militants died.
Witnesses in Gaza said tanks and bulldozers had moved towards the southern town of Khan Younis before withdrawing.
It was the first time Israeli soldiers had died in Gaza since Israel's 22-day offensive there more than a year ago.
Israel says the fighting started when its troops crossed into Gaza after spotting militants planting explosives along the border.
Reports from inside Gaza say the militants then tried to capture an Israeli soldier.
Unilateral ceasefires declared by both Israel and the Islamist movement Hamas after Israel's military operation in December 2008 and January 2009 have largely held.
Palestinians and human rights groups say more than 1,400 Gazans were killed in that operation, though Israel puts the figure at 1,166. Three Israeli civilians and 10 Israeli soldiers were also killed.
Hundreds of rockets have since been fired into southern Israel by militants in Gaza.
Update: The Gazan youth reported to have been shot and killed in this report later emerged uninjured. He had fled to Egypt through one of the tunnels under the border with the strip,
as reported here