Three Palestinians were killed in Jenin refugee camp in the West Bank early on Saturday after Israeli soldiers launched an operation to arrest a militant, Palestinian officials said.
Medical and security sources said two of those killed were militants and the third was a civilian. They said 14 Palestinians were also wounded, with two in critical condition.
The Palestinian sources said soldiers entered the camp in the northern West Bank city to arrest Hamza Abu Alheja, 20, a member of the Hamas military wing, the Ezzedine al-Qassam Brigades, with clashes resulting in the death of Mahmud Abu Zena, 19, an Islamic Jihad militant.
A civilian named as Yazan Jabarin was also killed in the clashes, the Palestinians said, as a day of mourning and general strike were announced.
Army spokesman Peter Lerner called Abu Alheja "a ticking bomb" who took part in shooting attacks and was in "advanced stages of the preparation of further attacks".
Lerner told reporters security forces shot Abu Alheja only after he shot and lightly wounded two Israelis while trying to escape from the building in which he was holed up.
Meanwhile, "Palestinians began to shoot and throw explosive devices at the troops, and as a result we have two more killed", Lerner added.
While there is security coordination between Israel and the Palestinian Authority (PA), the Palestinians were not involved in the Jenin operation, he said.
Israeli forces had previously tried to arrest Abu Alheja in a December raid that resulted in the death of an Islamic Jihad militant.
Defence Minister Moshe Yaalon said Saturday's incident "saved lives" since it "thwarted a terror attack that had already been planned and was supposed to target Israelis".
- 'End security coordination' -
Around 15,000 mourners calling for Palestinian unity and vengeance, as well as and end to Palestinian-Israeli peace talks, attended a joint funeral for the three dead men at noon.
An AFP correspondent said the bodies of Abu Alheja and Abu Zena were wrapped in flags of their Hamas and Jihad movements, while Jabarin was wrapped in the flag of the Al-Aqsa Martyrs Brigades, an armed offshoot of Palestinian leader Mahmud Abbas's Fatah party.
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A rare joint statement by the three movements issued during the funeral vowed revenge and accused the PA which is headed by Abbas of complicity in the killings through its security cooperation with Israel.
PA security forces had arrested Abu Alheja in the past.
Gaza rulers Hamas called on the PA to "end security coordination with the Israeli occupation and leave the resistance to act freely,” in a statement.
Abu Alheja's father, Jamal Abu Alheja, is a prominent leader of the Islamist movement Hamas who was been in Israeli prison since 2002.
An Islamic Jihad statement issued from Gaza said the Jenin killings demonstrated that "resistance continues".
"The United States and Israel want to force the Palestinians and the entire region to surrender, but Gaza and the West Bank resist this," senior Islamic Jihad official Nafez Azzam said.
The movement called for a demonstration in the northern Gaza town Beit Lahiya later Saturday to condemn the Jenin killings and "support resistance."
A spokesman for Abbas condemned the "continuing escalation against the Palestinian people", for which he blamed Israel.
"We call on the US administration to move quickly to prevent a general collapse in the region," Nabil Abu Rudeina said.
On Thursday, he said US-sponsored peace talks with Israel have reached an impasse because of Jewish settlement activity.
The talks are on the brink of collapse, with Washington fighting an uphill battle to get the two sides to agree to a framework proposal to extend the negotiations to the year's end after an April 29 deadline.
The violence in Jenin came as Palestinians in Gaza prepared to mark the 10th anniversary of the killing of Sheikh Ahmed Yassin, spiritual leader of Hamas, in an Israeli air strike.
Saturday's deaths mark the bloodiest clash in the West Bank since November, when Israel killed three men it said were Salafist militants.
Since the beginning of 2014, Israeli forces have killed nine Palestinians in the West Bank, according to an AFP tally.