Israeli troops raided a West Bank village in search of wanted militants, sparking a firefight that left two Palestinians dead, including an 11-year-old boy, Palestinian officials said.
In other violence on Friday, the Israeli army said it killed two Palestinian gunmen in the northern Gaza Strip after they opened fire at a border patrol.
Mahmoud Ibrahim Karnawi, 11, was shot after Israeli troops moved into the village of Saida in the northern West Bank, witnesses said.
The troops were trying to arrest his older half-brother, a wanted Islamic Jihad militant, and came under fire as they approached the family's home, setting off a gunfight, they said.
Neighbors said the boy was inside the home at the time of the shooting and hit in the crossfire.
Hospital officials in the nearby town of Tulkarem confirmed the death.
Tariq Mulhem, an Islamic Jihad militant not related to the boy, also was killed, the officials said.
Relatives said the boy lived in Israel with his parents.
The family was visiting relatives in the West Bank at the time of the shooting, the relatives said.
The army said its forces came under fire during an operation, sparking an exchange of fire in which two Palestinians were killed.
One of the dead was a gunman, but there were no details on the identity of the second, it said.
A member of the Israeli paramilitary border police was lightly wounded and treated at the scene, the army said, adding that troops confiscated two AK-47 rifles and ammunition.
Meanwhile in Gaza, the army said it killed two Palestinian militants who fired at soldiers on the Israeli side of the border.
The troops entered Gaza and shot the gunmen after a brief chase, the army said.
Palestinian medical officials said they were aware of the shootings, but could not immediately send ambulances to retrieve the bodies.
Also in Gaza, Hamas security agents clashed with supporters of the rival Fatah movement on Friday, firing into the air and beating journalists covering a demonstration against the Islamic militant group's rule in the Gaza Strip.
It was the second time in recent weeks that Hamas has scuffled with Fatah protesters, a signal of possible cracks in the Islamic group's two-month-old takeover of Gaza. Harassment of journalists and political opponents has grown increasingly common in the coastal strip.
The demonstrators gathered after weekly Muslim prayers in an open square in Gaza City organized by Fatah activists who say they have not been welcome in mosques since the Hamas takeover.
The protesters threw stones and bottles at a former Fatah security compound now used as headquarters of the Hamas paramilitary police. Hamas men fired guns over the heads of hundreds of demonstrators.
When several Hamas security men roughed up a Reuters TV cameraman and tried to confiscate his camera, protesters surrounded the Hamas men, beat them to the ground and prevented the journalist's arrest.
The Hamas men also detained a photographer for Agence France-Presse and a cameraman for the Russian TV channel Russia Today, along with two other reporters working for local news outlets.
They also broke a TV camera belonging to the Arabic-language TV network al-Arabiya.
All four detained journalists were quickly released and got their equipment back, Hamas officials and witnesses said.
Journalists later staged a protest against the crackdown.