Also, Fatah gunmen shot and wounded three Hamas activists after kidnapping them. One of the wounded was identified as a Hamas member of Ramallah's municipal council and a second as a Hamas preacher from a nearby village.
Fatah leaders said a decision was made by security commanders to crack down on Hamas in the West Bank, to prevent it from taking any positions in that territory, a Fatah stronghold.
"Last night, there was a decision by the leaders of the security forces to go after Hamas and to arrest them, before they think of bringing the war here," said Issam Abu Bakr, a Fatah leader in the West Bank city of Nablus. "This is true for all of the West Bank. Perhaps it was a belated decision, but now we can stand against Hamas and defend ourselves."
Arrests of Hamas activists were reported in the West Bank towns of Jenin, Nablus, Jericho, Ramallah and Bethlehem.
In Bethlehem, security forces wore ski masks, to avoid being identified, as they seized Hamas activists in their homes and businesses, witnesses said
In Nablus, masked security agents and Fatah gunmen rode together in cars, searching for Hamas members, and broke into several homes of Hamas activists. In one area, a brief firefight erupted.
In Ramallah's Al Quds University, Fatah-allied students kicked out Hamas supporters and forced a suspension of teaching, the officials said.
In Nablus, dozens of gunmen set fire to the third-floor office of several Hamas members of parliament and threw furniture into the street. Gunmen pulled one man into the street and hit him when he fought back, witnesses said.