Zayid Khalil Musa was the leader of the Izz al-Din al-Qassam Brigades, reports Aljazeera's correspondent in Jenin.
A Palestinian source said the resistance fighter had been killed by an Israeli undercover unit inside a building on Wednesday.
Another reports cites an Israeli military source as saying troops had shot dead an armed Palestinian man in an exchange of gunfire.
Aljazeera's correspondent reports that clashes between resistance fighters and Israeli forces are continuing in the town. Two fighters and an Israeli soldier have also been injured in the clashes.
Residents earlier said soldiers in around 25 jeeps had entered the town, surrounding several houses.
Elsewhere in the West Bank, Israeli occupation forces rolled into the town of Nablus at daybreak and engaged in clashes with stone-throwing youths.
At least six youth were wounded by rubber-coated bullets.
In Balata, two members of the al-Aqsa Martyrs Brigades, an armed offshoot of the ruling Fatah faction, were lightly wounded by Israeli gunfire, sources said.