Israeli forces wounded 20 Palestinians during a ground operation in northern West Bank town of Qalqilya on Wednesday, Palestinian medical sources said.
A hospital official said that Mohammed Daoud, 18, was critically injured in the head and would be transferred to another hospital in nearby Nablus city for further medication.
Other injuries were in moderate and minor conditions, the sources added.
Tens of Israeli army vehicles stormed large parts of the town before dawn and imposed curfew, witnesses said, adding that clashes broke out between the army and local fighters.
They also said that Israeli bulldozers demolished a number of houses in the town.
Hamas said the operation was meant to arrest a group of its militants who were holed up in a house.
The offensive comes a day after Israeli Prime Minister Ehud Olmert and Palestinian President Mahmoud Abbas held a meeting in Jerusalem, the second of its kind this month.